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Forestry plant seedling production uses non-eco-friendly polybags. Organic pots are a solution that can be applied. This research aimed to analyze the composition and size of raw materials in organic pots for balsa growth and to examine the composition of raw materials in organic pots appropriate for balsa growth. This study used a factorial complete randomized design (CRD). There are two factors: the organic pot composition factor (A) and the mesh size factor (M). The observed parameters included the C/N ratio of organic pots, height, diameter, biomass, and plant chlorophyll content. The results showed that the highest percentage decrease in the C/N ratio was found in the A3M2 treatment. The highest average value of balsa plant growth was found in the A3M2 treatment (15% newspaper, 80% goat manure, 5% cocopeat, and ten mesh material size). The highest chlorophyll content was found in A3M1 treatments (15% newspaper, 80% goat manure, 5% cocopeat, five mesh material size). Organic pots with low C/N ratio values had higher average increases in height and diameter of plants compared to organic pots with high C/N ratio values. The optimal composition of the organic pot in this study was the A3M2 treatment.

Copyright of Water & Landscape (WAL) / Agua & Territorio (AYT) is the property of Editorial de la Universidad de Jaen and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article deals with a detailed experimental study dedicated to the evaluation of the overall mechanical behaviour of a bio-based composite structure used in transportation industries. The sandwich structure is designed to increase the lightening, vibration damping, and composite recyclability. The considered materials consist of a Flax/Elium® laminate composite for skins associated with a balsa core. The sandwich structure was obtained using a one-shot liquid resin infusion process. Low-velocity impact tests were carried out on different sandwich configurations with the aim of characterizing the effects of the stacking sequence and the density and thickness of the core. Furthermore, an experimental comparative analysis was conducted involving two composite laminate types: Glass/Elium and Flax/Elium to enhance the specific behaviour of flax fibre composite to be used as skins in the sandwich structures. The impact tests were carried out at low velocities and at different levels of impact energy using a drop-weight test bench. Notable damage mechanisms have been identified, and a chronological sequence of their development has been suggested. Ultrasonic analyses using C-Scan imaging were applied to the opposite side of the impacted specimen. The research proves the efficient energy-absorbing capability of the biobased sandwich structure during impact. Finally, this study enables a deeper understanding of various parameters that influence the behaviour of sandwiches during low-velocity impacts, thereby facilitating more informed material selection for practical applications.

Sandwich composites are often used as primary load-bearing structures in various industries like aviation, wind, and marine due to their high strength-to-weight and stiffness-to-weight ratios, but they are vulnerable to damage from Low-velocity-impact (LVI) events like dropped tools, hail, and birdstrikes. This often manifests in the form of Facesheet-Core-Debonding (FCD) and is often termed Barely-Visible-Impact-Damage (BVID), which is difficult to detect and can considerably reduce mechanical properties. In general, a balsa core sandwich is especially vulnerable to FCD under LVI as it has poorer adhesion than synthetic core materials. A cork core sandwich does show promise in absorbing LVI with low permanent indentation depth. This paper also reviews surface treatment/modification as a means of improving the adhesion of composite core and fiber materials: key concepts involved, a comparison of surface free energies of various materials, and research literature on surface modification of cork, glass, and carbon fibers. Since both balsa and cork have a relatively low surface free energy compared to other materials, this paper concludes that it may be possible to use surface modification techniques to boost adhesion and thus FCD on balsa or cork sandwich composites under LVI, which has not been covered by existing research literature. [ABSTRACT FROM AUTHOR]

Ecuador is one of the main balsa wood marketers, thanks to its subtropical zone which presents optimal geographical and climatic conditions that benefit its development. The balsa, O. pyramidale (Cav. ex Lam.) Urb., is a species native to the American tropics; It is frequently found in disturbed and degraded areas. The objective of this research was to determine the effects of five substrates on the propagation of Ochroma pyramidale (Cav. ex Lam.) Urb. seedlings in the Paján canton, province of Manabí. The research was carried out in the field from September to December 2020 in the Paján canton on the "LA RAQUELITA" Farm owned by Mr. Euclides Plaza, located at Km. 4 via Colimes, between the Geographic Coordinates 80°25'12" of west longitude and 01°34'12" south latitude, an altitude of 200 meters above sea level. The ecological zone is a very dry tropical forest type (bmsT), characterized by an average daily temperature of 25 °C, receives average annual rainfall of 1626 mm, with a pH of 7, relative humidity 86% and 1146.6 hours of sunshine per day. anus. The treatments under study were T1 Black earth 100% (Control), T2 (Black earth 75%, sand 25%), T3 (Black earth 50%, sand 25%, humus 25%), T4 (Black earth, 33%, sand 33%, humus 33%) and T5 (black earth 50%, humus 50%), the results indicate that the substrate made up of black earth 50%, humus 50% allows for better results in the propagation of Ochroma pyramidale (Cav. ex Lam.) Urb. in nursery stage. [ABSTRACT FROM AUTHOR]

The use of woods with a low density and good structural uniformity has intensified in recent decades, paving new ways for their superior valorization. This research study aimed to examine the wood of three deciduous wood species with low densities and great uniformity of structure, namely linden wood, with an oven-dried density of 461 kg/m3, paulownia wood, with an oven-dried density of 304 kg/m3, and balsa wood, with an oven-dried density of 118 kg/m3. The physical and mechanical properties of these species were studied using various methodologies. The obtained results show that, although they have significant differences in terms of densities and mechanical characteristics, the coloristic properties of the three analyzed species obtained using the CIELab are almost similar. As a general conclusion, based on all the properties found in this research, it can be concluded that paulownia wood is more appropriate than linden or balsa for use, being able to replace linden in its uses. [ABSTRACT FROM AUTHOR]

Sandwich composites were fabricated successfully with the balsa wood as core material and regenerated cellulose fabric bio-based polypropylene (PP) composite skins. The regenerated cellulose fabric PP composites were produced using two different methods: the conventional stacking lay-up and directly using PP pellets. Sandwich composites were made using the hot press equipment with the customized mold. The sandwich composite system and bio-composite laminate were designed to achieve very close weight to compare the key mechanical properties that each design can bear. It was evidenced from the experimental results that 416% increase in the bending load bearing property of the part can be obtained when sandwich structure was used. These experimental results were in close agreement with one of the analytical modelling utilised. The drop weight impact test results demonstrated that the sandwich specimen is capable of withstanding more than 6 kN load and absorbing the impact energy of 28.37 J.

Design / Build / Fly (DBF) is an annual and international remote controlled aircraft design competition that provides engineering students an opportunity to develop an aircraft that meets the competition requirements set by AIAA. This year’s competition requires teams to develop a short takeoff, carrier based aircraft with remotely folding wings and capable of carrying and releasing cargo. After analyzing the score analysis, our team determined that the highest scoring potential is to maximize the amount of stores carried while completing an equal number of laps within a 10 minute window. The team explored a wide range of options and finalized on an aircraft design that meets the given constraints while also excelling in mission performance. Our aircraft consists of a 75 in wingspan, an aspect ratio of 6.25, a maximum takeoff weight of 16 lbs, and a cargo capacity of 12 stores. Faculty Advisors: Professor Robert H. Liebeck; Advisors: Colin Sledge, Joseph Hsieh, Paul ParcelContact DBF Team • Nathan Yeung nhyeung@uci.edu • Marlon Sevilla marlonps@uci.edu • Brian Chen brianlc1@uci.eduEmail: dbf.uci.sdp@gmail.com Facebook: https://www.facebook.com/dbfuci/ For more information, visit: http://www.aiaadbf.org/

The world economy seeks to promote the sustainable use of forests and in this context, balsawood production is presented as a profitable option due to its demand in different countries and the versatility of its uses. To evaluate the profitability of the investment, it is important to determine the costs of both traditional and irrigated cultivation. In a descriptive research using a non-experimental method, the economic feasibility of implementing an irrigation system in the production of balsa in the province of Santa Elena was analyzed, comparing the costs and benefits of both cultivation methods. The results show that cost analysis is crucial to evaluate the profitability of the crop, and that the implementation of an irrigation system in dry areas, such as the province of Santa Elena, may be the best option to increase the production and profitability of the balsa crop. In addition, it was found that the use of the irrigation system allows obtaining a higher quality production in a shorter time. Therefore, investment in an irrigation system is a recommendable option for balsa production in dry areas, as it is reflected in the production and profitability of the crop. [ABSTRACT FROM AUTHOR]

The aim of this study is to analyze the properties of Paulownia tomentosa x elongata plantation wood from Serbia, considering the influence of the stem height (0 to 1 m and 4.5 to 6 m above soil level—height spot) and radial position from the pith to bark (in the core, near the bark, and in between these zones—cross-section spot). The results show that most properties are improved when the samples were taken from upper parts of the tree (height spot) and from the near bark spot (cross-section spot). The mean density measured 275 kg/m3 at the stem height between 4.5–6 m and 245 kg/m3 for the samples collected from 0–1 m trunk height. The density had the highest value on the spot near bark (290 kg/m3), for the mature wood at a height of 4.5–6 m, and near pith had a mean density of 230 kg/m3. The Brinell hardness exhibited highest values in the axial direction (23 N/mm2) and near bark (28 N/mm2). The bending strength was 41 N/mm2 for the trunk's height range of 4.5–6 m and 45 N/mm2 in the cross-section, close to cambium. The three-point modulus of elasticity (MOR) of the samples taken at a stem height of 4.5 to 6 m was up to 5000 N/mm2, and on the spot near bark, the MOR measured 5250 N/mm2. Regarding compressive strength, in the cross-section, near the pith, the mean value was the highest with 23 N/mm2 (4.5–6 m), whilst it was 19 N/mm2 near bark. The tensile strength was, on average, 40 N/mm2 for both 0–1 m and 4.5–6 m trunk height levels and 49 N/mm2 between bark and pith. The screw withdrawal resistance measured 58 N/mm for the samples extracted at a stem height of 4.5 to 6 m and 92 N/mm for the specimens collected near pith. This study stresses the influence, in short-rotation Paulownia timber, of indicators, such as juvenile and mature wood (difference emphasized after the fifth year of growth) and height variation, on the physical and mechanical properties of sawn wood. This study will help utilize more efficient sustainable resources, such as Paulownia plantation wood. This fast-growing hardwood species from Europe is adequate as a core material in sandwich applications for furniture, transport, sport articles, and lightweight composites, being considered the European Balsa. [ABSTRACT FROM AUTHOR]

Abstract Balsa (Ochroma pyramidale), which is the lowest density wood, is a useful species in various industries. In general, balsa can be divided into three types (low density: LD, middle density: MD, high density: HD). In this study, we classified the porosities of the three balsa types into through-pore porosity, blind-pore porosity, and closed-pore porosity. As a result, the total porosity of balsa showed a high positive (+) correlation with closed-pore porosity, but total porosity of balsa showed negative (−) correlations with blind-pore porosity and through-pore porosity. Such information can be useful when using balsa as a natural porous material.

The use of woods with a low density and good structural uniformity has intensified in recent decades, paving new ways for their superior valorization. This research study aimed to examine the wood of three deciduous wood species with low densities and great uniformity of structure, namely linden wood, with an oven-dried density of 461 kg/m3, paulownia wood, with an oven-dried density of 304 kg/m3, and balsa wood, with an oven-dried density of 118 kg/m3. The physical and mechanical properties of these species were studied using various methodologies. The obtained results show that, although they have significant differences in terms of densities and mechanical characteristics, the coloristic properties of the three analyzed species obtained using the CIELab are almost similar. As a general conclusion, based on all the properties found in this research, it can be concluded that paulownia wood is more appropriate than linden or balsa for use, being able to replace linden in its uses.

Renewed efforts towards greater use of environmentally sustainable materials have created new opportunities for balsa wood (Ochroma pyramidale) to replace non-renewable, petroleum-based cores such as polymer foams in a broad range of sandwich structures. This paper reviews published research into the applications, manufacturing, microstructure, mechanical properties and in-service performance of sandwich structures with balsa wood cores. The benefits of balsa wood in sandwich structure construction are reviewed, including environmental sustainability, low raw material cost, excellent specific mechanical properties, and thermal insulation properties. The potential challenges of balsa cores in sandwich structures are also evaluated, including potential global supply chain issues, limited applicability of part processing techniques, impact, blast and fire performance, as well as water durability. Published research into the underlying properties and mechanisms responsible for the benefits and limitations of balsa core sandwich structures are reviewed. Topics for further research to advance the characterisation and applications of balsa structural sandwich materials are also discussed.

Balsa (Ochroma pyramidale), which is the lowest density wood, is a useful species in various industries. In general, balsa can be divided into three types (low density: LD, middle density: MD, high density: HD). In this study, we classified the porosities of the three balsa types into through-pore porosity, blind-pore porosity, and closed-pore porosity. As a result, the total porosity of balsa showed a high positive (+) correlation with closed-pore porosity, but total porosity of balsa showed negative (−) correlations with blind-pore porosity and through-pore porosity. Such information can be useful when using balsa as a natural porous material. [ABSTRACT FROM AUTHOR]

This study focuses on the investigation of the effects of different core types on the low velocity impact, three-point bending and out-of-plane compression loading performance of sandwich composites. Three core materials were selected: Balsa wood, PVC foam, and Ayous wood. The facesheets of sandwich composites were produced by woven carbon/epoxy. Balsa and PVC foam are widely used in sandwich composites as core materials. In this study, Ayous wood, which is the lightest tree after Balsa, was used as core material in addition to traditional core materials. Woven carbon fiber fabrics with an areal density 200 g/m2 as reinforcement and epoxy matrix were used to produce the sandwich composite. Vacuum-assisted resin infusion molding method was used to manufacture composite panels. A number of tests under various impact energy levels for three different sandwich composites were conducted with Fractovis Plus impact testing machine in order to investigate the energy absorption capacity of sandwich composites. Maximum contact forces, absorbed energies, and the maximum deflections of sandwich panels were obtained for each impact energy level. Despite having the same facesheets, Ayous core sandwich composites possess a higher perforation threshold than Balsa and PVC foam sandwich composites. The perforation threshold of Balsa, PVC foam, and Ayous sandwich composites are 85, 72, and 170 J, respectively. In addition, the Ayous core sandwich composites have better bending and compression strengths. The bending strength of the Ayous sandwich composite is higher about six times than PVC sandwich composite and about two times than Balsa sandwich composite. [ABSTRACT FROM AUTHOR]

Daijun Zhou, Tao Yang, Wei Qian, Malcolm Xing, Gaoxing Luo Institute of Burn Research; State Key Laboratory of Trauma, Burn and Combined Injury; Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China Objective: This study aimed to prepare an eco-friendly dressing using a balsa-derived membrane with lysozymes designed for antibacterial purposes.Methods: The groups included controls, balsa (group A), translucent balsa (group B), translucent balsa–lysozymes (group C), and translucent balsa-modified lysozymes (group D). Physical and chemical methods were used to characterize the materials, and the function of the materials was evaluated by in vivo and in vitro experiments.Results: Antibacterial activity against Escherichia coli and Staphylococcus aureus was ordered D > C > B ≈ A (P C > B ≈ A > control (P C > B ≈ A > control (P C > B ≈ A > control (P0.05). The order of expression of axin was D < C < B ≈ A < control (P C > B ≈ A > control (P

Copyright of Boletín del Museo Chileno de Arte Precolombino is the property of Museo Chileno de Arte Precolombino and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Terahertz waves (T-ray) were extensively studied for the nondestructive evaluation of the characterization of trailing edges composed with composite materials. The NDE system consisted of both continuous wave (CW) and time domain spectroscopy (TDS). The FRP composites were utilized for both trailing edges of wind energy (non-conducting polymeric composites) and carbon fiber composites with conducting properties. The signals of T-ray in the TDS mode almost resembles that of ultrasound waves; however, a terahertz pulse could not penetrate a material with conductivity, unlike ultrasound. The refractive index (n) was utilized as one of the material properties, so a method was suggested to obtain the "n" in the materials. The data of refractive index (n) were utilized due to obtained data for the trailing edges. The trailing edges were scanned for charactering and inspecting. C-scan and B-scan images were obtained and the optimal NDE techniques were suggested for complicated geometry samples by terahertz radiation. In particular, the penetrating time-of-flight (TOF) of T-ray corresponded with the calculated TOF for the trailing edges with greater thickness (about 70 mm). [ABSTRACT FROM AUTHOR]

The Scolytinae is highly diversified in tropical forests, but richness and abundance patterns within most Ecuadorian forest habitat types are not yet characterized. Topics discussed include patterns of variation in Scolytinae richness, abundance, and species composition in a primary and a secondary natural forest, and a commercial balsa plantationin Ecuador. Survey of Scolytinae communities with baited traps and measured associated environmental variables.

Copyright of Journal of Economic Entomology is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Balsa wood (Ochroma pyramidalei) are widely available in Indonesian market especially in the creative industry. Balsa wood was preferred due to its excellent strength to weight ratio in-line with workability and the simplicity of its color and texture. Balsa composite has increased the economic value of balsa wood and widen its use from merely lightweights and non-structural objects to some efficient super-structures. The development of balsa composite into curved structure add another level of design sophistication and widen the variation of its use. Application of this material in a shell structure allowed the structure to have more strength to weight excellence, since the shell structure itself had already had excellent depth to span ratio. The added value of the application in Indonesia is expected to add significant contribution in national agroforestry and construction sector. However, introducing the material into construction industry required further examination, especially related to the stability of supplies (forestry management), manufacture readiness, and human resources. This paper showed a theoretical and statistical feasibility study of manufacture-scale business establishment in Indonesia. [ABSTRACT FROM AUTHOR]

El objetivo de la investigación fue establecer el aporte social, económico y ambiental que el cultivo de balsa provee al recurso suelo mediante la materia orgánica, al aire a través del carbono, a la economía ecuatoriana al proveer empleo, ingresos económicos para las familias, materia prima de calidad para la industria nacional e internacional, generando valor monetario (PIB) en la producción de bienes y servicios para el sector maderero del país. La valoración se basó en la metodología de la sostenibilidad fuerte, la variable de repuesta fue lo socioeconómico y ambiental, el primero se midió mediante el barómetro de sostenibilidad e indicador relación beneficio costo; el segundo (variables ambientales) se evaluó aplicando el método de valor de uso directo. Se utilizó un diseño completo al azar (DCA) en arreglo factorial para analizar el efecto de los tratamientos. Se estableció que la producción de balsa es rentable (RBC=3,6), genera empleo en el área rural, reduce la presión actual sobre los bosques nativos, presenta sostenibilidad fuerte, acumula carbono en el suelo 58,07 t ha-1 y biomasa 143,604 t ha-1, provee materia orgánica (107 Tm ha-1), brinda fuente de nutrientes para mantener la flora y fauna endémicas de la región. La balsa se ubica como cultivo resiliente del área rural al mitigar los gases efecto invernadero producto de las actividades agro productivas, generando sinergia entre bienestar humano y el bienestar del ecosistema, lo que conlleva a que cada ecuatoriano debe conservar 12 árboles para mantener su balance ambiental, en corresponsabilidad para las generaciones futuras y el desarrollo sostenible.

Conclui-se a análise iniciada no Boletim de Estudos Clássicos de 2014, da inscrição IRCP 73. Vamos procurar enquadrar na história e na sociedade romanas da época os eventos que o sêxviro organizou: um barcarum certamen et pugilum, assim como a entrega de dinheiro aos cidadãos.

Abstract This study evaluated the termite susceptibility of Papua New Guinea (PNG) balsa (Ochroma pyramidale) against Australia's most economically important wood-destroying termite species, Coptotermes acinaciformis. Samples of envelope treated PNG balsa with the insecticide bifenthrin and non-treated balsa, radiata pine (Pinus radiata) sapwood and southern blue gum (Eucalyptus globulus) heartwood were exposed to seven different colonies of C. acinaciformis at a field site in the Northern Territory, Australia. The results indicated that balsa is susceptible to termite attack, with a mean mass loss of 30.9% (range 3.8–99.9%). Mean mass losses for radiata pine and southern blue gum were 90.3 and 98.9% respectively. It was evident that balsa can be successfully protected from termite attack with envelope-treatments of bifenthrin, with the latter proving to be highly efficacious at mass/volume retentions much lower than those specified in AS 1604.1 and typically used in the Australian timber preservation industry. Highlights • PNG balsa is susceptible to wood-destroying termite attack in Australia, with a mean mass loss of 30.9% (range 3.9–99.9%). • Similarly, as a control in the study, the mean mass losses for radiata pine and southern blue gum were 90.3% and 98.9%. • Balsa can be successfully protected from termite attack with envelope-treatments of the insecticide bifenthrin. • The paper reviews the literature for balsa susceptibility to termite species and details the origin of balsa and methods used. [ABSTRACT FROM AUTHOR]

A study was undertaken with the aim to determine thermal properties of balsa wood grown in plantations in Papua New Guinea. Thermal conductivity values were measured using the needle probe procedure according to ASTM D5334 (2008). The mean thermal conductivity results of balsa were in the range of 0.0381 W/mK to 0.0665 W/mK, similar to other materials currently used as insulators in the construction industry. A balsa sample with a density of 113 kg m3 had the lowest thermal conductivity value, 0.0339 W/mK, across the tangential and radial wood grain directions. Balsa is exported from Papua New Guinea mostly as end-grain panels to international markets to optimise its strength properties in the axial direction for applications that are exposed to compressive forces. This study revealed that there is the opportunity for Papua New Guinea balsa processors to consider producing perpendicular-grain panels for insulation markets, as the mean thermal conductivity values in this direction can be as low as 0.0381 W/mK, which is much lower than the thermal conductivity of the current end-grain panels at 0.0665 W/mK. The finding creates a potential design opportunity for balsa processors to consider entering new commercial markets to promote Papua New Guinea-grown balsa.

Los sistemas digitales han crecido en complejidad y la velocidad del reloj aumenta continuamente, incrementando de la misma manera algunos problemas como el retraso de la señal de reloj, el rendimiento total del sistema y el consumo de potencia. Debido a esto se está experimentando un interés en el diseño de circuitos asíncronos, los cuales no manifiestan este tipo de problemas. Este trabajo presenta los resultados de la implementación asíncrona en hardware de las funciones de transformación del algoritmo criptográfico Threefish en su proceso de cifrado, con el fin de utilizar las bondades de los diseños asíncronos en criptografía. Para la especificación, síntesis y simulación asíncrona de los módulos de Threefish se usó una herramienta EDA (Electronic Design Automation) de distribución libre conocida como Balsa. Esta plataforma define su propio lenguaje de descripción de hardware, mientras la implementación se realizó sobre hardware reconfigurable a través de la plataforma ISE Design Suite de Xilinx Inc.

The effect of radial growth rate on wood properties was evaluated for 7-year-old balsa trees grown in plantationforest in East Java, Indonesia. The standing trees in the experiment site in theplantation were categorised into three groups (slow-, medium- and fast-growth) according to their stem diameter. Mean values of stem diameter, tree height and stress-wave velocity (SWV) were 311 mm, 25.4 m and 2.96 km/s, respectively. No significant correlations were found between growth characteristics and SWV of stems. The mean values of basic density, compressive strength parallel to grain, modulus of elasticity and modulus of rupture were 0.14 g/cm3, 10.4 MPa, 4.53 GPa and 22.9 MPa, respectively. The wood properties were almost constant up to 80-mm from the pith, and then they sharply increased toward the bark. Therefore, separation of the wood at around 80 mm from the pith is likely to be useful for wood industries. [ABSTRACT FROM AUTHOR]

The species of Scolytinae subfamily have a worldwide distribution, and are found mainly in the Neo-tropic regions. They usually dominate the communities of wood borer insects. The aim of the present study was to determine the diversity among Scolytinae species associated with balsa, teak, rubber and gamhar plantations located in the humid tropical zone of the Ecuadorian littoral. In each plantation seven flight interception traps containing an ethanol / gel mixture were installed, with a collection frequency of 15 days for three months in the dry period. A total of 1437 specimens were collected, represented by Xyleborini, Cryphalini, Corthylini and Ipini tribes. In the four plantations, 18 species of Scolitids were collected, of which 16 were recorded in the balsa plantation, while in the other plantations 10 to 12 species were found. The most abundant Scolitids were Hypothenemus spp., Corthylus spp., Xyleborus affinis, Xyleborinus bicornatulus and Premnobium cavipennis. The Shannon-Wiener diversity index was higher in the balsa culture (H'= 2.37) and lower in Teak (H'= 1.57). The Jaccard similarity index was higher among the teak and rubber plantations (Cj = 0.9090) while the balsa plantation obtained less similarity with respect to the other three plantations. The greatest diversity of Scolitids was recorded in the balsa plantation, which is a native species, unlike the other forest species, which are exotic, indicating that the diversity would be influenced by the host tree and the location where they are found. [ABSTRACT FROM AUTHOR]

Coptoborus ochromactonus, is a recently described scolytid pest associated with the balsa plantations, causing damage and death in young trees (from 12 to 36 months). The objectives were: Characterize the distribution of damage into the tree, define the incidence of C. ochromactonus in two years old plantations in Buena Fe and El Empalme, and evaluate dasometrics parameters of its host. C. ochromactonus has two types of damages that correspond to the initial attack, when the shaft is unsuccessful and no mass attack, whereas when it occurs in upper branches and exceed 300 drillings produces symptoms of dieback and then spike the shaft. The incidence of injury was higher in El Empalme 22.90%, attacking trees 20.10 cm dbh and 18.40 m high, relative to Buena Fe, with 11.20%, 18.20 attacking trees dbh cm and 15.90 m high. [ABSTRACT FROM AUTHOR]

The hierarchical structure of the hardwood balsa ( Ochroma pyramidale ) is modelled sequentially at various length scales to describe the contribution of each to its elastic moduli. The model takes into account the main features of the microstructure at each length scale, including the orthotropic properties of cellulose microfibrils, the microfibrillar angle, the thickness of cell wall layers, as well as the geometry and arrangement of the cells: the rays, fibres and vessels. Similar to some multi-scale models proposed for softwoods, at each length scale, a representative unit cell of the material is identified and the effective stiffness matrix is determined using finite element analysis with appropriate periodic boundary conditions. A comprehensive search in the literature was conducted to obtain input values for the model. The results of the model, over a wide range of densities, gives a good description of experimentally measured values. The model highlights the significance of cellulose crystallinity, microfibrillar angle and the ray and fibre cell geometries (including the density) in determining the overall elastic constants of balsa. In the future, the model can be used as a tool to design lightweight cellular composites with optimized cell wall composition and cell geometry. [ABSTRACT FROM AUTHOR]

Natural fiber and wood are environmentally friendly materials with multiscale microstructures. The sound absorption performance of flax fiber and its reinforced composite, as well as balsa wood, were evaluated using the two-microphone transfer function technique with an impedance tube system. The microstructures of natural materials were studied through scanning electrical microscope in order to reveal their complex acoustical dissipation mechanisms. The sound absorption coefficients of flax fiber fabric were predicted using a double-porosity model, which showed relatively accurate results. The integrated natural materials sandwich structure was found to provide a superior sound absorption performance compared to the synthetic-materials-based sandwich structure composite due to the contribution of their multiscale structures to sound wave attenuation and energy dissipation. It was concluded that the natural-materials-based sandwich structure has the potential of being used as a sound absorption structure, especially at high frequency.

With the development of technology, the use of glass fibres and sandwich structures in a wide variety of engineering applications has had important growth in recent years because of their low self-weight and high strength when compared to conventional materials. Moreover, natural materials can be used as the core material in sandwich structures instead of conventional materials. Since synthetic materials cause a reduction of carbon release during material formation, these kinds of materials are renewable and recyclable. Therefore, in sandwich structures, renewability and recycling can be provided. In this study, dynamic properties of natural material-based sandwich composites were investigated experimentally and numerically. The effects of the thickness of the core and fibre orientation and number of layers on frequency and damping were analysed. It was observed that if the core thickness of the structure is properly optimised, this sandwich structure demonstrates better dynamic properties. Thus, sandwich materials from natural origin may offer more environmental friendly solutions compared to other materials. [ABSTRACT FROM AUTHOR]