scholarly journals A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel ( Hamamelis mollis OLIV., Hamamelidaceae)

2019 ◽  
Vol 16 (157) ◽  
pp. 20190327 ◽  
Author(s):  
Simon Poppinga ◽  
Anne-Sophie Böse ◽  
Robin Seidel ◽  
Linnea Hesse ◽  
Jochen Leupold ◽  
...  
Keyword(s):  
Shape Change ◽  
Rotational Velocity ◽  
Three Dimensional ◽  
Apical Part ◽  
Middle Part ◽  
Fine Tuning ◽  
Mechanical Pressure ◽  
Witch Hazel ◽  
Rotation Direction ◽  
Morphological Differences

The fruits of Chinese witch-hazel ( Hamamelis mollis , Hamamelidaceae) act as ‘drying squeeze catapults', shooting their seeds several metres away. During desiccation, the exocarp shrinks and splits open, and subsequent endocarp deformation is a complex three-dimensional shape change, including formation of dehiscence lines, opening of the apical part and formation of a constriction at the middle part. Owing to the constriction forming, mechanical pressure is increasingly applied on the seed until ejection. We describe a structural latch system consisting of connective cellular structures between endocarp and seed, which break with a distinct cracking sound upon ejection. A maximum seed velocity of 12.3 m s −1 , maximum launch acceleration of 19 853 m s −2 (approx. 2000 g ) and maximum seed rotational velocity of 25 714 min −1 were measured. We argue that miniscule morphological differences between the inner endocarp surface and seed, which features a notable ridge, are responsible for putting spin on the seed. This hypothesis is further corroborated by the observation that there is no preferential seed rotation direction among fruits. Our findings show that H. mollis has evolved similar mechanisms for stabilizing a ‘shot out’ seed as humans use for stabilizing rifle bullets and are discussed in an ecological (dispersal biology), biomechanical (seed ballistics) and functional–morphological (fine-tuning and morphospace of functional endocarps) contexts, and promising additional aspects for future studies are proposed.

scholarly journals Evaluating the Irrigation Effect of Continuous Flushing During Up-and-down Motion of Instruments Using a Computational Fluid Dynamics Model

2020 ◽  
Author(s):  
Linxi Guo ◽  
Xin Shi ◽  
Xiangfen Li ◽  
Yuanxi Zhao ◽  
qin su
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Static Solution ◽  
Apical Part ◽  
Middle Part ◽  
Original Solution ◽  
Mechanical Preparation ◽  
Irrigation Effect ◽  
Computational Fluid Dynamics Cfd

Abstract Background:The viscous environment caused by the rotation of Nickel-titanium (Ni-Ti) instruments in a static solution inside the root canal during mechanical preparation may increase the difficulty of endodontic debridement and the risk of instrument fatigue fracture. Therefore, this study aimed to investigate the effect of continuous flushing during up-and-down motion of instruments using a three-dimensional computational fluid dynamics (CFD) numerical model.Results:After30s simulation,water entering the canal formed an "efficient replacement area" in upper part of the canal and transported to the apical part of the canal.Increasing the velocity and amplitude of the motion of the instrument caused less time of flushing water to reach the apical area; and the replacement of the original solution was primarily improved by increasing the amplitude.Conclusions:Continuous flushing during up-and-down movement of the instrument significantly helped to rapidly replace the original solution with water at the coronal and middle part of the canal and dilutedthe viscosity of the original solution to some extend in the whole canal.It is therefore beneficial to add continuous water flushing to the instruments used in the preparation process.Furthermore, the amplitude of the movement in file’s up-and-down motion should be appropriately increased to improve its irrigation effect in clinical practice.

SEISMIC VULNERABILITY ASSESSMENT FOR SAN FRANCISCO TEMPLE IN MORELIA, MEXICO

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 207-2016
Author(s):  
Guillermo Martinez ◽  
David Castillo ◽  
José Jara ◽  
Bertha Olmos
Keyword(s):  
San Francisco ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Middle Part ◽  
Seismic Demands ◽  
Modeling And Analysis ◽  
Seismic Records ◽  
Cracking Pattern ◽  
The Temple

This paper presents a first approximation of the seismic vulnerability of a sixteenth century building which is part of the historical center of Morelia, Mexico. The city was declared World Heritage by United Nations Educational, Scientific and Cultural Organization in 1991. The modeling and analysis of the building was carried out using a three-dimensional elastic tetrahedral finite elements model which was subjected to probabilistic seismic demands with recurrences of 500 yrs and 1000 yrs in addition to real seismic records. The model was able to correctly identify cracking pattern in different parts of the temple due to gravitational forces. High seismic vulnerability of the arched window and the walls of the middle part of the bell tower of the temple was indicated by the seismic analysis of the model.

Residual-limb shape change: three-dimensional CT scan measurement and depiction in vivo.

Radiology ◽  
1996 ◽  
Vol 200 (3) ◽  
pp. 843-850 ◽  
Author(s):  
K E Smith ◽  
P K Commean ◽  
M W Vannier
Keyword(s):  
Ct Scan ◽  
Shape Change ◽  
Three Dimensional ◽  
Residual Limb

Taxonomic description and 3D modelling of a new species of myzostomid (Annelida, Myzostomida) associated with black corals from Madagascar

Zootaxa ◽  
2017 ◽  
Vol 4244 (2) ◽  
pp. 277 ◽  
Author(s):  
LUCAS TERRANA ◽  
IGOR EECKHAUT
Keyword(s):  
New Species ◽  
Phylogenetic Analyses ◽  
Three Dimensional ◽  
Close Relation ◽  
Ventral Side ◽  
Middle Part ◽  
The Body ◽  
Taxonomic Description ◽  
Black Corals ◽  
Organ Systems

Eenymeenymyzostoma nigrocorallium n. sp. is the first species of myzostomid worm associated with black corals to be described. Endoparasitic specimens of E. nigrocorallium were found associated with three species of antipatharians on the Great Reef of Toliara. Individuals inhabit the gastrovascular ducts of their hosts and evidence of infestation is, most of the time, not visible externally. Phylogenetic analyses based on 18S rDNA, 16S rDNA and COI data indicate a close relation to Eenymeenymyzostoma cirripedium, the only other species of the genus. The morphology of E. nigrocorallium is very unusual compared to that of the more conventional E. cirripedium. The new species has five pairs of extremely reduced parapodia located on the body margin and no introvert, cirri or lateral organs. Individuals are hermaphroditic, with the male and female gonads both being located dorsally in the trunk. It also has a highly developed parenchymo-muscular layer on the ventral side, and the digestive system lies in the middle part of the trunk. A three-dimensional digital model of this worm’s body plan has been constructed whereby the external morphology and in toto views of the observed organ systems (nervous, digestive and reproductive) can be viewed on-screen: http://doi.org/10.13140/RG.2.2.17911.21923. 

Formalizing shape-change: Three-dimensional printed shapes and hygroscopic material transformations

2019 ◽  
Vol 18 (1) ◽  
pp. 67-83
Author(s):  
Elena Vazquez ◽  
Benay Gürsoy ◽  
Jose Pinto Duarte
Keyword(s):  
Shape Change ◽  
Three Dimensional ◽  
Fourth Dimension ◽  
Dynamic Nature ◽  
Three Dimensional Printing ◽  
Responsive Systems ◽  
Hygroscopic Material ◽  
Wood Based Composite ◽  
Dimensional Printing ◽  
Printing Parameters

Shape-changing materials have become increasingly popular among architects in designing responsive systems. One of the greatest challenges of designing with these materials is their dynamic nature, which requires architects to design with the fourth dimension, time. This article presents a study that formalizes the shape-changing behavior of three-dimensional printed wood-based composite materials and the rules that serve to compute their shape-change in response to variations in relative humidity. In this research, we first developed custom three-dimensional printing protocols and analyzed the effects of three-dimensional printing parameters on shape-change. We thereafter three-dimensional printed kirigami geometries to amplify hygroscopic material transformation of wood-based composites.

Experimental Study on Mechanical Properties of Rubber Used for Damping Bearing

2011 ◽  
Vol 189-193 ◽  
pp. 1132-1136 ◽  
Author(s):  
Yong Xu Zhao ◽  
Wen Jun Hu ◽  
Jun Mei ◽  
Niu Wei ◽  
Jian Jun Xie
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Three Dimensional ◽  
Middle Part ◽  
Loading Conditions ◽  
Deflection Curve ◽  
Rubber Bearing ◽  
Components Analysis ◽  
The Impact ◽  
Load Deflection Curve

After testing on T-type rubber bearing under tensile, compression and shear mechanical properties under different temperature in this paper. Obtained load deflection curve and destructive mode under different loading conditions at -40 and normal temperature of rubber components. Analysis the impact of temperature and the loading conditions that effect on load-elongation and destructive mode of T-type damping rubber structure. It showed that T-end rubber bearing has different kinds of deformation under different force-giving methods. Under compression, the stress pattern of the rubber bearing is three-dimensional and middle rubber bear the greatest force. Under tensile loading, the middle part of the rubber contract and the side with smaller lateral section has greater shrinkage; moreover, damage occurred in the area with stress concentration and weak strength. Under shearing action, extrude faces appeared with crinkle and damage occurred in the middle part of extrude faces. At the low temperature-40 , rubber support still has great elastic properties. The low temperature has a big effect on tensile properties and has little effect on damage properties.

Tuning of relative spatial distributions of a two-component ion system to improve sympathetic cooling efficiency

2021 ◽  
pp. 2150352
Author(s):  
Li-Jun Du ◽  
Yan-Song Meng ◽  
Yu-Ling He ◽  
Jun Xie
Keyword(s):  
Spatial Configuration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Fine Tuning ◽  
Charge Ratio ◽  
Spatial Distributions ◽  
Cooling Efficiency ◽  
Dynamic Coupling ◽  
Sympathetic Cooling ◽  
Secular Motion

Herein, a fine-tuning method is proposed for the spatial distributions of a mixed three-dimensional (3D) ion system in dual radio frequency (RF) linear Paul traps to achieve efficient sympathetic cooling. The dual RF field matching, efficient capture method and transient process of the intrinsic micromotion of the mixed ion system are analyzed quantitatively by numerical simulations. The 3D correlation coupling characteristics between intrinsic micromotion and secular motion of ion system are obtained. It is found that reasonable low-frequency trapping potential can produce ultra-low-frequency pulling effect on ions with low mass-to-charge ratio (M/Q), which is beneficial to the dynamic coupling between ions with large M/Q differences. The effects of equivalent stiffness coefficients [Formula: see text] on the relative spatial configuration and dynamic coupling process of mixed 3D ion crystals with large M/Q differences are discussed. By tuning [Formula: see text], radial distributions of laser-cooled ions (LCIs) and sympathetically cooled ions (SCIs) that do not conform to the rules based on M/Q are realized. The optimum sympathetic-cooling efficiency occurs, where [Formula: see text] is approximately equivalent to [Formula: see text]. These results are applicable to studies such as cold ion clocks, quantum logic manipulation, antimatter synthesis, regulation of cold chemical reaction, and precise spectral measurements based on sympathetic cooling.

Mechanical evaluation of theories of neurulation using computer simulations

Development ◽  
1993 ◽  
Vol 118 (3) ◽  
pp. 1013-1023 ◽  
Author(s):  
D. A. Clausi ◽  
G. W. Brodland
Keyword(s):  
Computer Simulations ◽  
Driving Forces ◽  
Shape Change ◽  
Three Dimensional ◽  
Dorsal Surface ◽  
Neural Plate ◽  
Neural Tube Closure ◽  
Amphibian Embryo ◽  
Axial Elongation ◽  
Shape Changes

Current theories about the forces that drive neurulation shape changes are evaluated using computer simulations. Custom, three-dimensional, finite element-based computer software is used. The software draws on current engineering concepts and makes it possible to construct a ‘virtual’ embryo with any user-specified mechanical properties. To test a specific hypothesis about the forces that drive neurulation, the whole virtual embryo or any selected part of it is ascribed with the force generators specified in the hypothesis. The shape changes that are produced by these forces are then observed and compared with experimental data. The simulations demonstrate that, when uniform, isotropic circumferential microfilament bundle (CMB) constriction and cephalocaudal (axial) elongation act together on a circular virtual neural plate, it becomes keyhole shaped. When these forces act on a spherical (amphibian) embryo, dorsal surface flattening occurs. Simulations of transverse sections further show that CMB constriction, acting with or without axial elongation, can produce numerous salient transverse features of neurulation. These features include the sequential formation of distinct neural ridges, narrowing and thickening of the neural plate, skewing just medial to the ridges, ‘hinge’ formation and neural tube closure. No region-specific ‘programs’ or non-mechanical cell-cell communications are used. The increase in complexity results entirely from mechanical interactions. The transverse simulations show how changes to the driving forces would affect the patterns of shape change produced. Hypotheses regarding force generation by microtubules, intercellular adhesions and forces extrinsic to the neural plate are also evaluated. The simulations show that these force-generating mechanisms do not, by themselves, produce shape changes that are consistent with normal development. The simulations support the concept of cooperation of forces and suggest that neurulation is robust because redundant force generating mechanisms exist.

EFFECTS OF ALVEOLAR MORPHOLOGY ON ALVEOLAR MECHANICS: AN EXPERIMENTAL STUDY OF MOUSE LUNG BASED ON TWO- AND THREE-DIMENSIONAL IMAGING METHODS

2019 ◽  
Vol 19 (04) ◽  
pp. 1950027
Author(s):  
TIANYA LIU ◽  
YUXING WANG ◽  
XIAOYU LIU ◽  
LAN YUAN ◽  
DEYU LI ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Shape Change ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Spherical Shape ◽  
Mouse Lung ◽  
Three Dimensional Imaging ◽  
Lung Injuries ◽  
Mouse Lungs ◽  
Alveolar Mechanics

Understanding alveolar mechanics is important for preventing the possible lung injuries during mechanical ventilation. Alveolar clusters with smaller size are found having lower compliance in two-dimensional studies. But the influence of alveolar shape on compliance is unclear. In order to investigate how alveolar morphology affects their behavior, we tracked subpleural alveoli of isolated mouse lungs during quasi-static ventilation using two- and three-dimensional imaging techniques. Results showed that alveolar clusters with smaller size and more spherical shape had lower compliance. There was a better correlation of sphericity rather than circularity with alveolar compliance. The compliance of clusters with great shape change was larger than that with relatively slight shape change. These findings suggest the contribution of lung heterogeneous expansion to lung injuries associated with mechanical ventilation.

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