The Structure and Histochemistry of the Nectary and Anther Secretory Tissue of the Flowers of Thryptomene calycina (Lindl) Stapf (Myrtaceae)

1989 ◽  
Vol 37 (1) ◽  
pp. 65 ◽  
Author(s):  
DV Beardsell ◽  
EG Williams ◽  
RB Knox
Keyword(s):  
Food Source ◽  
Secretory Cells ◽  
Floral Tube ◽  
Wide Range ◽  
Pollinating Insects ◽  
Secretory Tissue ◽  
Thin Walled ◽  
Vascular Connections ◽  
Hydrophobic Material

Flowers of Thryptomene calycina contain two types of secretory tissue. Nectaries of the floral tube secrete a nectar rich in fructose and glucose, probably through the numerous stomata in the epidermis. The secretory cells are densely packed and have few vascular connections. The five anther connectives each terminate in a gland, which at anthesis contains large, thin-walled cells. The gland contains a hydrophobic material which stains positively for lipids and probably contains phenolics. This material is secreted through a pore at the end of the gland where it collects and mixes with pollen to form a food source for insects. This dual secretion of food materials would ensure that a wide range of pollinating insects visit the flowers.

Energy absorbed ability and damage analysis for honeycomb sandwich material of bio-inspired micro aerial vehicle under low velocity impact

2020 ◽  
pp. 095440622097542
Author(s):  
Jianxun Du ◽  
Peng Hao ◽  
Mabao Liu ◽  
Rui Xue ◽  
Lin’an Li
Keyword(s):  
Honeycomb Structure ◽  
Low Velocity Impact ◽  
Parameter Study ◽  
Low Velocity ◽  
Micro Aerial Vehicle ◽  
Thin Walled Structures ◽  
Wide Range ◽  
Aerial Vehicle ◽  
Thin Walled ◽  
The Impact

Because of the advantages of light weight, small size, and good maneuverability, the bio-inspired micro aerial vehicle has a wide range of application prospects and development potential in military and civil areas, and has become one of the research hotspots in the future aviation field. The beetle’s elytra possess high strength and provide the protection of the abdomen while being functional to guarantee its flight performance. In this study, the internal microstructure of beetle’s elytra was observed by scanning electron microscope (SEM), and a variety of bionic thin-walled structures were proposed and modelled. The energy absorption characteristics and protective performance of different configurations of thin-walled structures with hollow columns under impact loading was analyzed by finite element method. The parameter study was carried out to show the influence of the velocity of impactor, the impact angle of the impactor and the wall thickness of honeycomb structure. This study provides an important inspiration for the design of the protective structure of the micro aerial vehicle.

scholarly journals Clock genes in calendar cells as the basis of annual timekeeping in mammals--a unifying hypothesis

2003 ◽  
Vol 179 (1) ◽  
pp. 1-13 ◽  
Author(s):  
GA Lincoln ◽  
H Andersson ◽  
A Loudon
Keyword(s):  
Gene Expression ◽  
Molecular Mechanism ◽  
Clock Genes ◽  
Prolactin Secretion ◽  
Secretory Cells ◽  
Dark Phase ◽  
Pars Tuberalis ◽  
Cry Protein ◽  
Wide Range

Melatonin-based photoperiod time-measurement and circannual rhythm generation are long-term time-keeping systems used to regulate seasonal cycles in physiology and behaviour in a wide range of mammals including man. We summarise recent evidence that temporal, melatonin-controlled expression of clock genes in specific calendar cells may provide a molecular mechanism for long-term timing. The agranular secretory cells of the pars tuberalis (PT) of the pituitary gland provide a model cell-type because they express a high density of melatonin (mt1) receptors and are implicated in photoperiod/circannual regulation of prolactin secretion and the associated seasonal biological responses. Studies of seasonal breeding hamsters and sheep indicate that circadian clock gene expression in the PT is modulated by photoperiod via the melatonin signal. In the Syrian and Siberian hamster PT, the high amplitude Per1 rhythm associated with dawn is suppressed under short photoperiods, an effect that is mimicked by melatonin treatment. More extensive studies in sheep show that many clock genes (e.g. Bmal1, Clock, Per1, Per2, Cry1 and Cry2) are expressed in the PT, and their expression oscillates through the 24-h light/darkness cycle in a temporal sequence distinct from that in the hypothalamic suprachiasmatic nucleus (central circadian pacemaker). Activation of Per1 occurs in the early light phase (dawn), while activation of Cry1 occurs in the dark phase (dusk), thus photoperiod-induced changes in the relative phase of Per and Cry gene expression acting through PER/CRY protein/protein interaction provide a potential mechanism for decoding the melatonin signal and generating a long-term photoperiodic response. The current challenge is to identify other calendar cells in the central nervous system regulating long-term cycles in reproduction, body weight and other seasonal characteristics and to establish whether clock genes provide a conserved molecular mechanism for long-term timekeeping.

An Evaluation of Material Weight and Contained Fluid Volume for Eccentric Intersecting Cylinders of Arbitrary Size

1989 ◽  
Vol 111 (3) ◽  
pp. 342-347
Author(s):  
Y. J. Chao ◽  
M. A. Sutton
Keyword(s):  
Vessel Diameter ◽  
Fluid Volume ◽  
Wide Range ◽  
Single Integral ◽  
Material Volume ◽  
Thin Walled ◽  
Special Case ◽  
Range Of Values ◽  
Engineering Personnel ◽  
Quantities Of Interest

Engineering personnel in industries which use pressurized containment vessels having attached nozzles are required not only to design portions of the lifting mechanism, but also to estimate the fluid volume which the vessel and nozzles will contain; most designers use simplified formulas for computing the quantities of interest. Typically, these formulas are valid approximations when the nozzle diameter is much smaller than the vessel diameter. The enclosed work develops three single-integral expressions which can be programmed and numerically integrated to obtain accurate estimates for both the material volume and also the containment volume present in a pair of eccentrically, or concentrically, intersecting thin-walled cylinders of arbitrary diameters. A table of such values is presented for a wide range of values of the standard nozzle pipe diameter and vessel diameter, for the special case of a concentric nozzle. In addition, an example is presented which compares the numerically integrated values for both the material volume and the containment volume to simplified upper and lower-bound estimates.

scholarly journals New material-saving technologies of pipe rolling on pilgrim units

2021 ◽  
Vol 6 (131) ◽  
pp. 149-162
Author(s):  
Valery Balakin ◽  
Stanislav Stasevsky ◽  
Yuri Ugryumov
Keyword(s):  
Continuous Casting Machine ◽  
Cast Billet ◽  
Continuous Cast ◽  
Centrifugally Cast ◽  
Continuous Cast Billet ◽  
Wide Range ◽  
New Material ◽  
Thin Walled ◽  
Pilger Rolling ◽  
Material Saving

In this work, based on the analysis of the process of hot pilger rolling of pipes of a wide range of sizes and grades from a round continuous cast billet, new and improved existing metal-saving technologies have been developed to reduce metal losses in the pilger head.Using scientific and patent sources of information in the field of pilger rolling and its mathematical modeling with the calculation of tables for rolling pipes of a wide range of sizes from a round continuous-cast billet with a diameter of 385-470 mm, metal losses into technological scrap on a pilgerstan are determined: a seed and a pilger head.On the basis of the results of the theoretical determination of metal losses in the process scrap on the pilgerstan: the seed and the pilger head, a forecast was made to reduce the weight of the pilger head, which was used to develop new material-saving technologies for pilger rolling of pipes, both thick-walled with D / S = 6 - 12.5, and thin-walled with D / S = 12.5 - 40. Metal losses in the pilger head are the main factor of increased metal consumption coefficients on pilger units, which reduces their competitiveness in comparison with other units when using round continuously cast billets as a starting material.The forecast for the reduction of metal losses in the pilger head made for the first time makes it possible to estimate the reserves for reducing the mass of the pilger head both by eliminating the underflow of the liner and trimming of the pipe end adjacent to the pilger head, and by means of individual parts of its profile part and predicting its decrease to the minimum possible size, ensuring the removal of the pipe from the mandrel using a gate device.To reduce the weight of the pilger head when rolling thick-walled pipes, it is recom-?ended to use improved technologies for butt-end rolling and rolling of the pilger head on the free section of the mandrel.The results of the studies and the proposed new material-saving technologies can be used on pilgrim units when rolling thick-walled (D / S = 6 - 12.5) and thin-walled (D / S = 12.5 - 40) pipes of a wide range of brands (carbon, alloyed, highly alloyed and special) from both continuous casting machine and forged and centrifugally cast billets, as well as ingots.

Testing of Thin-Walled Tubular Workpieces

2016 ◽  
Vol 684 ◽  
pp. 483-486 ◽  
Author(s):  
S.G. Simagina
Keyword(s):  
Stressed State ◽  
Practical Importance ◽  
Complex Stressed State ◽  
Aviation Industry ◽  
Material Strength ◽  
Industrial Growth ◽  
Strength Performance ◽  
Wide Range ◽  
Physical Task ◽  
Thin Walled

In accordance with the Russian Federation State program called “Industrial growth and improving competitiveness” it becomes more wide-spread to use thin-walled makes for pieces, modern materials with new treating methods in mechanical engineering, in automobile production and modern aviation industry. As well as requirements for quality and mechanical characteristics of finished products constantly grow. In relation to these standards, methods of intensive irreversible deformation under conditions of complex stressed state are used with increasing frequency. Study of the following parameters has a great practical importance: loaded capability of the makes during exploitation and work material strength performance under complex production process. Such strain tasks are frequently counted as most complex and demand experimental verification because of geometric and physical task nonlinearity.The current study proposes testing method for thin-walled tubular workpieces which combines implementation simplicity with a wide range of strain-stressed state charts.

Influence of Geometric Features of the Peripheral Part of the Thin-Walled Spherical Segment on the Explosive Throwing Process

2020 ◽  
pp. 76-87
Author(s):  
M.A. Baburin ◽  
V.D. Baskakov ◽  
S.V. Eliseev ◽  
K.A. Karnaukhov ◽  
V.A. Tarasov
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Rotation ◽  
Aerodynamic Coefficients ◽  
Peripheral Part ◽  
High Speed Impact ◽  
Wide Range ◽  
Main Factors ◽  
Thin Walled ◽  
Axisymmetric Shape

The main factors controlling the formation of the stern of explosively formed projectiles are investigated using numerical calculations in a three-dimensional formulation of a problem. To form folds in the stern, it is proposed to use thin-walled spherical segments with a peripheral thickness deviation in terms of decreasing or increasing with respect to the thickness in the central part. The configurations of explosively formed projectiles with inclined folds in the stern are shown, and it is proposed to describe the fold inclination by two angles of its position. The effect of folds in the stern on the change in aerodynamic coefficients for a wide range of angle of attack is numerically studied. The angular velocity of the axial rotation of explosively formed projectiles with inclined folds in the stern is estimated based on the Newton method and considering the angles of its position. The results obtained are of interest to specialists working in the field of physics of explosion and high-speed impact, as well as those dealing with aerodynamics of aircrafts, mainly of axisymmetric shape

scholarly journals Numerical Analysis for U-Shaped Thin-Walled Structure Reinforced Timber Beam Based on Thin-Layer Beam Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Hui Liu ◽  
Jun Hu ◽  
Guohui Li ◽  
Guangying Mo
Keyword(s):  
Thin Layer ◽  
Beam Theory ◽  
Accurate Solution ◽  
Alloy Sheet ◽  
Element Analysis ◽  
Rational Engineering ◽  
Proposed Model ◽  
Wide Range ◽  
Thin Walled ◽  
Beam Height

This paper presents a theoretical model, taking into account the shear deformation subjected to the influence of U-shaped member by geometric parameters as flange height based on thin-layer beam theory, to analyze the structural bending behavior of U-shaped member reinforced timber composite beams, and the feasible design forms of U-section have been pointed out. The algorithm for this composite beam is the most practical and effective method to meet the accurate solution. The formulas for the common forms of U-section are presented. It aims to develop a rational engineering approach. The proposed model has been validated by comparing the results obtained in the present analysis with experimental results and finite element analysis. Furthermore, the results suggested that the value of flange height can be one-fifth the beam height based on the present analysis by comparison of two types of beams. And it is shown that the model provided here correlates consistently and satisfactorily with a wide range of timber beams reinforced by a thin-walled structure such as steel or aluminum alloy sheet bonded to their tension faces.

scholarly journals Influence of the Cut Axial Depth on Surface Roughness at High-Speed Milling of Thin-Walled Workpieces

2021 ◽  
Vol 20 (2) ◽  
pp. 127-131
Author(s):  
A. I. Germashev ◽  
V. A. Logominov ◽  
S. I. Dyadya ◽  
Y. V. Kozlova ◽  
V. A. Krishtal
Keyword(s):  
High Speed ◽  
End Milling ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Work Piece ◽  
Natural Vibration Frequency ◽  
High Speed Milling ◽  
Wide Range ◽  
Thin Walled ◽  
Axial Depth

The paper presents the results of research on the dynamics of end milling of thin-walled work-pieces having complex geometric shapes. Since the milling process with shallow depths of cut is characterized by high intermittent cutting, the proportion of regenerative vibrations decreases, and the effect of forced vibrations on the dynamics of the process, on the contrary, increases. The influence of  axial depth of cut on the vibrations arising during processing, and roughness of the processed surface have been studied in paper.  The experiments have been carried out in a wide range of changes in the spindle speed at different axial cutting depths.  Vibrations of a thin-walled work-piece  have been recorded with an inductive sensor and recorded in digital form. Then an oscillogram has been used to estimate the amplitude and frequency of oscillations. The profilograms of the machined surface have been analysed. Roughness has been evaluated by the parameter Ra. The results have shown similar relationships for each of the investigated axial cutting depths. The worst cutting conditions  have been observed when the natural vibration frequency coincided with the tooth frequency or its harmonics. It is shown that the main cause of vibrations in high-speed milling  is forced rather than regenerative vibrations. Increasing the axial depth of cut at the same spindle speed increases the vibration amplitude. However, this does not significantly affect the roughness of the processed surface in cases when it comes to vibration-resistant processing.

scholarly journals The structure of the spur nectary in Dendrobium finisterrae Schltr. (Dendrobiinae, Orchidaceae)

2012 ◽  
Vol 64 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Magdalena Kamińska ◽  
Małgorzata Stpiczyńska
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Single Layer ◽  
Secretory Cells ◽  
Vascular Bundles ◽  
Nectar Guides ◽  
Floral Nectary ◽  
Transmission Electron ◽  
Secretory Tissue ◽  
The One

To date, the structure of the nectary spur of <i>Dendrobium finisterrae</i> has not been studied in detail, and the present paper compares the structural organization of the floral nectary in this species with the spurs of other taxa. The nectary spur of <i>D. finisterrae</i> was examined by means of light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is composed of a single layer of secretory epidermis and several layers of small and compactly arranged subepidermal secretory cells. The secretory cells have thick cellulosic cell walls with primary pits. The secretory tissue is supplied by vascular bundles that run beneath in ground parenchyma and are additionally surrounded by strands of sclerenchymatous fibers. The flowers of the investigated species displayed morphological features characteristic of bee-pollinated taxa, as they are zygomorphic, creamy-green coloured with evident nectar guides. They also emit a weak but nice scent. However, they possess some characters attributed to bird-pollinated flowers such as a short, massive nectary spur and collenchymatous secretory tissue that closely resembles the one found in the nectaries of certain species that are thought to be bird-pollinated. This similarity in anatomical organization of the nectary, regardless of geographical distribution and phylogeny, strongly indicates convergence and appears to be related to pollinator-driven selection.

scholarly journals Toxicity of neem and pyrethrum extracts to adult grass grub

2002 ◽  
Vol 55 ◽  
pp. 298-302
Author(s):  
M.S. Qureshi ◽  
T.A. Jackson ◽  
R.J. Townsend ◽  
D.J. Saville
Keyword(s):  
Food Source ◽  
Botanical Insecticides ◽  
Direct Effects ◽  
Laboratory Bioassay ◽  
Chronic Effects ◽  
Wide Range ◽  
Costelytra Zealandica ◽  
Acute And Chronic Effects ◽  
Practical Implications ◽  
Root Feeding

Grass grub Costelytra zealandica larvae damage pastures and crops by root feeding while the adult beetles can be serious defoliators of a wide range of plants Control of this pest with botanical insecticides has received little attention The objectives of this study were to investigate the direct effects of neem and pyrethrum extracts on the adult beetle A laboratory bioassay was used to test the acute and chronic effects of the botanicals over a range of doses by treating a food source (Pittosporum tenuifolium) with the extracts Pyrethrum had the faster action; at all doses beetles were killed within a day Neem caused only low mortality even at the highest rate Similar results were obtained when the bioassays were repeated using the same treatments for Smiths chafer (Odontria smithii) beetle Further research is needed on the practical implications of these results

Sign in / Sign up

Export Citation Format

Share Document