scholarly journals Vesicular virgular apparatus in the graptolite Orthograptus calcaratus

1987 ◽  
Vol 35 ◽  
pp. 115-124
Author(s):  
M. Bjerreskov
Keyword(s):  
Cross Sections ◽  
Distal Part ◽  
Carbon Film ◽  
Free Part ◽  
Fat Globules ◽  
New Type ◽  
Full Relief ◽  
Life Function

A pyritized virgular apparatus (nematularium) has been observed in Orthograptus calcaratus s.l. (Lap­worth) from the Pleurograptus linearis Zone in the Ordovician Dicellograptus Shale on Bornholm, Den­mark. Specimens preserved in full relief show the free part of the nematularium to be circular in cross sec­tion, 0.5 mm in diameter, surrounded by a carbon film, and infilled with pyrite. The surface is covered by rounded elongated hummocks that generally are irregularly arranged but in a few cases lie in one row or are paired. SEM investigations of cross sections reveal that the nematularium has internal carbonized membranes surrounding vesicular tissue. These virgular structures form in the distal part of the thecae portion of the rhabdosome. This new type of vesicular nematularium is unique as earlier observations on other diplograptids showed the nematularia to be single-walled, with two or three vanes. The formation of the vesicular virgular ap­paratus and its life function is discussed: it most likely had a floating and/or stabilizing function, and may have contained buoyant material, such as vacuolated tissue with fat globules or gas inclusions.

Improvement and FEA of New Type of Osteointegrated Implant for Higher Amputated Leg Attachment

2007 ◽  
Vol 342-343 ◽  
pp. 829-832
Author(s):  
J.M. Luo ◽  
L. Zheng ◽  
X.H. Shi ◽  
Yao Wu ◽  
Xing Dong Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Distal Part ◽  
Element Analysis ◽  
Bone Stress ◽  
Traditional Design ◽  
Maximal Stress ◽  
New Type ◽  
Scan Data ◽  
Leg Prosthesis

Stress concentration is one of the main mechanical problems leading to the failure of clinical application for osteointegrated implant of percutaneous osteointegrated prosthesis, which is especially marked for higher amputated leg prosthesis. Traditionally design was composed of only the distal part. To improve the biomechanical safety, a new design with the lag part similar to the lag screw was introduced. Based on CT scan data, relatively accurate model of femur for finite element analysis (FEA) were obtained. The FEA results with the new implant demonstrated that compared to traditional design, the declination of bone stress peak ranged from 15.68% to 28.67%, perpendicular deformation from 34.73% to 72.16%, and maximal stress of implant from 14.51% to 23.36% with the increasing of loads from 3750N to 2000N. So the new design of osteointegrated implant would be more secure mechanically, in the case of higher amputated leg attachment.

Study on the Performance of Nano-CaCO3 and LLDPE Based Artificial Turf Fibers

2011 ◽  
Vol 332-334 ◽  
pp. 1077-1081
Author(s):  
Hong Ling Yi ◽  
Wei Shan Wang ◽  
Heng Lin ◽  
Wei Guang Gong ◽  
Ting Wei ◽  
...  
Keyword(s):  
Cross Sections ◽  
Tensile Force ◽  
Accelerated Aging ◽  
Artificial Turf ◽  
Sem Images ◽  
Crystallinity Degree ◽  
Elongation At Break ◽  
Caco3 Content ◽  
New Type ◽  
Strength Retention

In this paper, a new type of LLDPE/nano CaCO3 composite based artificial turf yarns with good tensile property and UV resistance is introduced. The effect of nano CaCO3content on tensile properties shows that the tensile force reached the maximum value when the CaCO3 content is about 7wt%, and the elongation at break gets to the highest point at 10wt%. After 3000h UV accelerated aging, the nano-CaCO3 and LLDPE based artificial turf fiber yarns has tensile strength retention about 87%, and the elongation at break is higher than LLDPE. DSC results shows that with the increase of nano-CaCO3 content, the crystallization temperature gradually increased, and the crystallinity degree declined. SEM images of cross sections of monofilament fibers show that nano CaCO3 had a good dispersion in monofilament fiber matrix. These reasons give rise to the improved mechanical properties of turf yarns.

Experimental investigation on new low cycle fatigue precision cropping process

2014 ◽  
Vol 229 (8) ◽  
pp. 1470-1476 ◽  
Author(s):  
Renfeng Zhao ◽  
Shengdun Zhao ◽  
Bin Zhong ◽  
Yong Tang
Keyword(s):  
Stress Concentration ◽  
Cross Sections ◽  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
High Energy ◽  
Concentration Effect ◽  
Cycle Fatigue ◽  
Stable Crack Propagation ◽  
New Type ◽  
Stress Concentration Effect

The traditional cropping processes have some disadvantages, such as poor surface quality, low yield, the waste of materials, and high energy consumption. The low cycle fatigue precision cropping process with circumferential loading, which is a new type of precision cropping process, is studied. According to the stress concentration effect of the V-shape notch, the fatigue crack on the tip of the V-shape notch is prompted to initiate and extend. The working principle of the precision cropping machine is described. The criterion that whether the crack on the root of the V-shape notch is initiated or not is provided under the effect of low cycle fatigue loading. The materials which are 0.2%C steel, H59 copper, 0.45%C steel, 20Cr steel, and LY12 aluminum are tested under two control curves. The initiation and propagation of crack are accelerated and the good cross sections of the metal bar are obtained. The results show that the mean stress of the metal bar in the cropping process can be effectively reduced due to the stress concentration effect of the V-shape notch. The metal bar’s stable crack propagation and fracture can be obtained when constantly increasing striking displacement and reducing the striking frequency in the cropping process at the same time in the process.

Heavy Ion-Induced Characteristic X-Ray Generation as an Analytical Probe

1970 ◽  
Vol 14 ◽  
pp. 173-183 ◽  
Author(s):  
J. A. Cairns ◽  
D. F. Holloway ◽  
R. S. Nelson
Keyword(s):  
Cross Sections ◽  
Heavy Ions ◽  
Proton Irradiation ◽  
Heavy Ion ◽  
X Rays ◽  
X Ray ◽  
The Past ◽  
Tracer Techniques ◽  
New Type ◽  
Gas Volume

AbstractIncreasing attention is currently focused on the generation of characteristic x-ray by proton irradiation. This has the advantage of yielding “clean” x-ray- i. e. free from background brerasstrahlung radiation, from even the lightest elements. The disadvantage is that the yields are naturally much lower than those produced by electrons of the same energy. A recent study has extended characteristic x-ray production to a variety of heavy ions and has shown that the cross- sections for the production of clean x-rays are often higher , by as much as several orders of magnitude, than those produced by protons of the same energy. In addition, there has emerged a further advantage, viz. the ability of specially chosen heavy ions to excite characteristic x-ray from a particular element in a selective manner. Since heavy ions penetrate only a few hundred Angstroms in to most solids, the phenomenon can be used as the basis of a technique for the examination of surface deposits, or to measure depth distributions of impurities. For example, Kr ions can be used t o determine the range distribution of antimony which had been implanted in to silicon at 100 keV. The antimony concentration was determined as a function of ∼ 150 Å steps, and was found to exhibit a maximum concentration of ∼ 1 part in 103 of silicon at 450 Å below the surface, falling to zero concentration at ∼2000 Å a depth. In the past, in order to obtain the required degree of sensitivity, such range determinations have relied on radio active tracer techniques.An entirely new type of proportional counter has been developed during the course of these studies. This instrument, because of its special construction, can be positioned very close to targets in non-dispersive studies, so as to collect the highest possible fraction of emitted x-ray. It incorporates a replaceable anode unit, together with a built- in miniature head amplifier, and exhibits extremely good performance, particularly for ultra-soft x-ray. In addition, rotation of a dial on the end of the counter body allows alteration of the active gas volume during operation, and so permits tuning into x-rays of a particular energy.

A NEW PROBE FOR COHERENT MANY-BODY DYNAMICS: NONERGODIC MOLECULES IN CONTINUUM

2002 ◽  
Vol 11 (04) ◽  
pp. 273-280 ◽  
Author(s):  
S. YU. KUN ◽  
A. V. VAGOV ◽  
L. T. CHADDERTON ◽  
W. GREINER
Keyword(s):  
Cross Sections ◽  
Reaction Dynamics ◽  
Polyatomic Molecules ◽  
Many Body ◽  
Physical Explanation ◽  
Energy Redistribution ◽  
Nuclear Collisions ◽  
Nuclear Molecules ◽  
Body Dynamics ◽  
New Type

We present a simple physical explanation that measurements of the collision cross-sections with pure energy resolution can provide information on the reaction dynamics equivalent to that obtained using real-time methods of femtochemistry. For nuclear collisions, the method provides a time resolution of ~ 10-21 sec. The method is sensitive enough to distinguish between the different scenarios of rotational dephasing for the highly-excited nuclear molecules, with strongly overlapping resonances, formed in 12C + 24Mg scattering. We find that the dephasing is much slower than the intra-molecular energy redistribution. This reveals unusual states — nonergodic molecules in continuum. Anomalously long dephasing times observed in highly-excited polyatomic molecules may reflect this new type of nonergodicity.

Hydrogen-bond-reversal symmetry and its violation in ice nanotubes

2016 ◽  
Vol 72 (3) ◽  
pp. 395-405 ◽  
Author(s):  
Mikhail V. Kirov
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Cross Sections ◽  
Combinatorial Problem ◽  
Hydrogen Atoms ◽  
Black And White ◽  
Unit Cells ◽  
New Type ◽  
The Asymmetry ◽  
Comprehensive Classification

Recently, a new type of generalized symmetry of ice structures was introduced which takes into account the change of direction of all hydrogen bonds. The energy nonequivalence of pairs of configurations with opposite direction of all hydrogen bonds was established in the course of computer simulation of bilayer ice and other four-coordinated structures without `dangling' hydrogen atoms. In this article, the results of detailed investigations of the violation of the hydrogen-bond-reversal symmetry in ice nanotubes consisting of stackedn-membered rings are presented. A comprehensive classification of all possible hydrogen-bonding configurations and their division into two classes (antisymmetrical and non-antisymmetrical) are given. Attention is focused on the most stable configurations that have no longitudinally arranged water molecules. This restriction made the asymmetry very difficult to find. For example, it was established that the asymmetry (non-antisymmetrical configurations) in ice nanotubes with square, pentagonal and hexagonal cross sections appears only when the number of transverse rings in the unit cell is more than six. It is shown that this is related to the well known combinatorial problem of enumerating the symmetry-distinct necklaces of black and white beads. It was found that, among the ice nanotubes that had been considered, hydrogen-bond-reversal asymmetry is most conspicuous in wide nanotubes such as heptagonal and octagonal. In this case the asymmetry is observed for unit cells of any length. In order to verify the results of the symmetry analysis and to confirm the energy nonequivalence of some (non-antisymmetrical) configurations, approximate calculations of the binding energy have been performed using the packageTINKER.

A NEW TYPE OF SEISMIC CROSS‐SECTION WHEREIN ACCURACY OF REPRESENTATION IS RENDERED INSENSITIVE TO VELOCITY ERROR

Geophysics ◽  
1945 ◽  
Vol 10 (2) ◽  
pp. 171-185 ◽  
Author(s):  
Phil P. Gaby
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Practical Method ◽  
Time Section ◽  
Velocity Error ◽  
Time Map ◽  
New Type ◽  
The Cross

A method is presented which was designed to: 1. Simplify computations in areas where velocity is known to vary, or may later be found to vary, laterally. 2. Considerably reduce the amount of recomputation necessitated by subsequent revisions in velocity. The conventional time‐section and time‐map satisfy these requirements but are indicated generally to be subject to serious errors, as illustrated. The proposed system is explained and evaluated. Advantages believed to be peculiar to it are tabulated, and a practical method of plotting the cross‐sections is presented.

scholarly journals PTFE Based Multilayer Micro-Coatings for Aluminum AlMg3 Forms Used in Tire Production

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 119
Author(s):  
Jan Novotny ◽  
Stefan Michna ◽  
Iryna Hren ◽  
Jaromir Cais ◽  
Irena Lysonkova ◽  
...  
Keyword(s):  
Cross Sections ◽  
Surface Defects ◽  
Light And Electron Microscopy ◽  
Microstructural Characterization ◽  
Functional Surface ◽  
Force Microscopy ◽  
Production Cycles ◽  
New Type ◽  
Tire Production ◽  
The Individual

The basic prerequisite for obtaining the coating of good quality is the production of a layer without the occurrence of surface defects. A possible solution to the occurrence of defects on the functional surface of the form is the application of a polytetrafluoroethylene (PTFE)-based coating. The coating helps to reduce surface roughness and “smooth” defects like pores and micro-shrinkage. For this reason, a new type and methodology of the coating were prepared to achieve more production cycles between the individual cleaning processes during the production of a tire. The subject of the study was the analysis of surface-applied micro-coatings, including the analysis of chemical composition by using energy-dispersive X-ray (EDX) and microstructure in the area of coatings. Detailed microstructural characterization of Alfipas 7818 and Alfiflon 39 and its imaging of surface structures were studied using atomic force microscopy. To examine the surface layer of the coatings, metallographic specimens of cross-sections (by means of a mold) were prepared and examined by light and electron microscopy. This new multilayer micro-coating with a thickness of 20–25 μm has been found to prevent form contamination during tire production and to extend production cycles by 200–400% between process cleanings. This finding was actually tested in the production of tires in the environment of a large manufacturing company.

The Carbon Film Electric Hygrometer Element

1954 ◽  
Vol 35 (2) ◽  
pp. 60-62 ◽  
Author(s):  
Walter J. Smith ◽  
Nancy J. Hoeflich
Keyword(s):  
Polarization Effect ◽  
Carbon Film ◽  
High Sensitivity ◽  
Performance Data ◽  
Rapid Response ◽  
Film Performance ◽  
New Type ◽  
Manufacturing Techniques ◽  
Film Element

A new type of electric hygrometer, the “carbon film element” is described. Its response to humidity changes is by electronic rather than electrolytic conduction. Main features of the new element are: high sensitivity to moisture changes, rapid response, absence of polarization effect, and a calibration independent of temperature between 0° and 40° C. Components of the carbon film, performance data, and manufacturing techniques are described.

Sign in / Sign up

Export Citation Format

Share Document