128 research outputs found
Cellulose lattice strains and stress transfer in native and delignified wood
Small specimens of spruce wood with different degrees of delignification were studied using in-situ tensile tests and simultaneous synchrotron X-ray diffraction to reveal the effect of delignification and densification on their tensile properties at relative humidity of 70â80âŻ%. In addition to mechanical properties, these analyses yield the ratio of strains in the cellulose crystals and in the bulk, which reflects the stress-transfer to crystalline cellulose. While the specific modulus of elasticity slightly increases from native wood by partial or complete delignification, the lattice strain ratio does not show a significant change. This could indicate a compensatory effect from the decomposition of the amorphous matrix by delignification and from a tighter packing of cellulose crystals that would increase the stress transfer. The reduced strain to failure and maximum lattice strain of delignified specimens suggests that the removal of lignin affects the stress-strain behavior with fracture at lower strain levels
A quantitative synthesis of the medicinal ethnobotany of the Malinké of Mali and the Ashåninka of Peru, with a new theoretical framework
<p>Abstract</p> <p>Background</p> <p>Although ethnomedically and taxonomically guided searches for new medicinal plants can improve the percentage of plants found containing active compounds when compared to random sampling, ethnobotany has fulfilled little of its promise in the last few decades to deliver a bounty of new, laboratory-proven medicinal plants and compounds. It is quite difficult to test, isolate, and elucidate the structure and mechanism of compounds from the plethora of new medicinal plant uses described each year with limited laboratory time and resources and the high cost of clinical trials of new drug candidates.</p> <p>Methods</p> <p>A new quantitative theoretical framework of mathematical formulas called "relational efficacy" is proposed that should narrow down this search for new plant-derived medicines based on the hypothesis that closely related plants used to treat closely related diseases in distantly related cultures have a higher probability of being effective because they are more likely to be independent discoveries of similar plant compounds and disease mechanisms. A prerequisite to this hypothesis, the idea that empirical testing in traditional medicine will lead to choosing similar medicinal plants and therefore the medicinal flora of two distant cultures will prove to be more similar than their general flora, is tested using resampling statistics on cross-cultural field data of the plants used by the MalinkĂ© of Mali and the AshĂĄninka of Peru to treat the diseases malaria, African sleeping sickness, Chagas' disease, leishmaniasis, diabetes, eczema, asthma, and uterine fibroids.</p> <p>Results</p> <p>In this case, the similarity of the medicinal floras is found to be significantly greater than the similarity of the general floras, but only when the diseases in question are grouped into the categories of parasitic and autoimmune diseases.</p> <p>Conclusion</p> <p>If the central theoretical framework of this hypothesis is shown to be true, it will allow the synthesis of medicinal plant information from around the world to pinpoint the species with the highest potential efficacy to take into the laboratory and analyze further, ultimately saving much field and laboratory time and resources.</p> <p><b>Spanish abstract</b></p> <p>Las bĂșsquedas que utilizan la etnomedicina y la taxonomĂa para descubrir nuevas plantas medicinales, pueden aumentar la probabilidad de Ă©xito de encontrar compuestos quĂmicos activos en plantas, en comparaciĂłn con las bĂșsquedas aleatorias. A pesar de lo anterior, en las Ășltimas dĂ©cadas, la etnobotĂĄnica no ha cumplido con las expectativas de proveer numerosas plantas medicinales y quĂmicos nuevos una vez examinados en el laboratorio. Cada año se describen una plĂ©tora de plantas medicinales y sus usos, sin embargo las limitaciones de tiempo y recursos en los laboratorios, unidos al alto coste de los ensayos clĂnicos de las drogas potenciales, hacen muy difĂcil probar, aislar, y elucidar la estructura y el mecanismo de los compuestos de estas plantas. Se propone un nuevo marco teĂłrico cuantitativo cuyo fin es focalizar la bĂșsqueda de nueva plantas medicinales. Este marco teĂłrico estĂĄ basado en la hipĂłtesis que las plantas cercanamente relacionadas, usadas para tratar enfermedades cercanamente relacionadas en culturas distantemente relacionadas, tienen una eficacia potencial mĂĄs alta, debido a que es mĂĄs probable que estos hallazgos sean descubrimientos independientes de compuestos quĂmicos similares. Parte de esta hipĂłtesis, que las escogencias racionales se hacen para elegir plantas medicinales similares y que la flora medicinal de dos culturas distantes es mĂĄs similar que su flora general, se probĂł usando mĂ©todos estadĂsticos de remuestreo con datos de campo de la comunidad MalinkĂ© de MalĂ y de la AshĂĄninka de PerĂș, y las enfermedades de paludismo, enfermedad africana del sueño, enfermedad de Chagas, leishmania, diabetes, eczema, asma, y fibromas uterinos. Se encontrĂł, en este caso, que la similitud de las floras medicinales es significativamente mayor a la similitud de las floras generales, solamente cuando las enfermedades analizadas se agruparon en las categorĂas de enfermedades parasitarias y enfermedades autoinmunes. Si se demostrara que las otras partes de esta hipĂłtesis son ciertas, se podrĂa sintetizar la informaciĂłn sobre plantas medicinales alrededor del mundo, para establecer asĂ las plantas potencialmente mĂĄs eficaces para llevarlas al laboratorio y analizarlas mĂĄs profundamente.</p> <p><b>French abstract</b></p> <p>Par rapport aux recherches menĂ©es de façon alĂ©atoire, les recherches effectuĂ©es par des critĂšres ethnobotaniques et taxonomiques ont de meilleures chances Ă dĂ©couvrir de nouvelles plantes mĂ©dicinales Ă produit chimique actifs. Pendant les derniĂšres dĂ©cennies pourtant, l'ethnobotanique a rĂ©alisĂ© peu de ces promesses Ă rĂ©vĂ©ler un grand nombre de plantes mĂ©dicinales et de nouveaux produits chimiques, testĂ©s au laboratoire. Avec les ressources limitĂ©es pour la recherche au laboratoire et le coĂ»t Ă©levĂ© des Ă©preuves cliniques pour trouver de nouveaux candidats aux mĂ©dicaments, il est difficile d'Ă©tudier, d'isoler et d'Ă©lucider la structure et le mĂ©canisme des produits chimiques de chacune des nombreuses plantes mĂ©dicinales (et les utilisations de ces plantes) dĂ©crites chaque annĂ©e. Nous proposons une nouvelle technique thĂ©orique et quantitative pour prĂ©ciser la recherche de nouvelles plantes mĂ©dicinales; elle est basĂ©e sur l'hypothĂšse que les plantes Ă©troitement apparentĂ©es, employĂ©es pour traiter les maladies Ă©troitement apparentĂ©es dans les cultures trĂšs Ă©loignĂ©es les unes des autres, ont une potentialitĂ© d'efficacitĂ© supĂ©rieure parce qu'elles reprĂ©sentent la dĂ©couverte indĂ©pendante des propriĂ©tĂ©s chimiques semblables des plantes. Une partie de cette hypothĂšse-qui dĂ©montre que la sĂ©lection des plantes mĂ©dicinales semblables est un choix rationnel et qu'il y a davantage de ressemblance dans la flore mĂ©dicinale de deux cultures Ă©loignĂ©es que dans leur flore gĂ©nĂ©rale-est examinĂ©e par un re-Ă©chantillonnage des donnĂ©es de recherches effectuĂ©es parmi les MalinkĂ© au Mali et les AshĂĄninka au PĂ©rou, en particulier sur la malaria, la maladie africaine du sommeil, la maladie de Chagas, la leishmania, le diabĂšte, l'eczĂ©ma, l'asthme et les fibromes utĂ©rins. Dans ces cas prĂ©cis, la similitude de la flore mĂ©dicinale s'avĂšre sensiblement plus grande que la similitude de la flore gĂ©nĂ©rale, mais seulement quand les maladies en question sont regroupĂ©es ensemble comme maladies parasitaires et auto-immunitaires. Si cette hypothĂšse est prouvĂ©e, elle permettra la synthĂšse des informations recueillies sur les plantes mĂ©dicinales du monde entier pour en sĂ©lectionner de façon plus prĂ©cise celles qui sont les plus efficaces et qui mĂ©ritent analyse plus approfondie au laboratoire.</p> <p><b>AshĂĄninka abstract</b></p> <p>Aayiantyarori irĂČpero aavintane, ontzimatye ancovacovatero ayotero ovaqueraripaye incashi iyoyetziri ashaninka, ayotzityaro aajatzi iyotane viracocha paitachari "quimica" ancantero aaca oshintsinka inchashipaye. Atziri yotacotzirori cametsa, ishtoriajacotzirori iyotane ashaninkapaye te iroñà rantero maaroni ocaratzi yamenacotaqueri laboratorioki. Aaviantyarori cametsa, ayotacotero aavintarontsiyetatsiri osamani antzimaventero ishtoriatacotaro, aajatzi osheki opinata ampinaventero aparopaye inchashi, acoviriqui ayotacotero, osaretsikipaye. Tzimatsi ovaquerari quenquishiriantsitatsiri ero opinata osheki ashitoriatacotero aparopaye inchashi, asampiyetatyrey pashinipaye atziri saicatsiri intaina puitarika inchasshi yavintari, ajatzirica oshiyaro ayotzi aaca, quemetachari atziri saikatsiri nampitsiki malinke aajatzi ishiyari ashaninka saicatsiri peruki, tzimatsi inchashi aajatzi yaavintari osheki okamĂštsatzi aririka anteri mantsiyarentsi icantaitziri ompetarentsi catsirentsi, pochokirentsi, patsarontsi(matatsi) ashipetate maaroni, ampochavathate, ancainikentsite, oncatsithakite tsinani. Aririka añaker aajatzi ahiyaro inchashi yaavintayetari pashinipaye atziri intainasatzi irdotake ahitoriatacoperoteri anĂ ashityard aavintarontsi ovamairiri shithanentsi, onĂ shitaavintarontsi tzicaacoventairi ero antane mantsiyarentsi. Omanperotatyarica irĂČperotzi avintarontsi, oshitovake laboratorioki aritaque iyoitanaquero maaroni quipatsiki iroperori avintarontsi.</p
Non-destructive detection of cross-sectional strain and defect structure in an individual Ag five-fold twinned nanowire by 3D electron diffraction mapping
Coherent x-ray diffraction investigations on Ag five-fold twinned nanowires (FTNWs) have drawn controversial conclusions concerning whether the intrinsic 7.35° angular gap could be compensated homogeneously through phase transformation or inhomogeneously by forming disclination strain field. In those studies, the x-ray techniques only provided an ensemble average of the structural information from all the Ag nanowires. Here, using three-dimensional (3D) electron diffraction mapping approach, we non-destructively explore the cross-sectional strain and the related strain-relief defect structures of an individual Ag FTNW with diameter about 30 nm. The quantitative analysis of the fine structure of intensity distribution combining with kinematic electron diffraction simulation confirms that for such a Ag FTNW, the intrinsic 7.35° angular deficiency results in an inhomogeneous strain field within each single crystalline segment consistent with the disclination model of stress-relief. Moreover, the five crystalline segments are found to be strained differently. Modeling analysis in combination with system energy calculation further indicates that the elastic strain energy within some crystalline segments, could be partially relieved by the creation of stacking fault layers near the twin boundaries. Our study demonstrates that 3D electron diffraction mapping is a powerful tool for the cross-sectional strain analysis of complex 1D nanostructures
Enhanced phosphorus removal in a waste stabilization pond system with blast furnace slag filters
Tumores de células gigantes do esfenóide: relato de 3 casos e revisão da literatura
Imaging of plant cell walls by confocal Raman microscopy
Raman imaging of plant cell walls represents a nondestructive technique that can provide insights into chemical composition in context with structure at the micrometer level (<0.5.mu m). The major steps of the experimental procedure are described: sample preparation (embedding and microcutting), setting the mapping parameters, and finally the calculation of chemical images on the basis of the acquired Raman spectra. Every Raman image is based on thousands of spectra, each being a spatially resolved molecular 'fingerprint' of the cell wall. Multiple components are analyzed within the native cell walls, and insights into polymer composition as well as the orientation of the cellulose microfibrils can be gained. The most labor-intensive step of this process is often the sample preparation, as the imaging approach requires a flat surface of the plant tissue with intact cell walls. After finishing the map (acquisition time is similar to 10 min to 10 h, depending on the size of the region of interest and scanning parameters), many possibilities exist for the analysis of spectral data and image generation
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