The Internal Structure of Coir (Coconut) Fiber

1985 ◽  
Vol 43 ◽  
pp. 644-645
Author(s):  
Leo Barish
Keyword(s):  
Cross Section ◽  
Sodium Hypochlorite ◽  
Vascular Strand ◽  
Coir Fiber ◽  
Dilute Solution ◽  
Coconut Fiber ◽  
Large Area ◽  
General Shape ◽  
Sem Study ◽  
High Degree

The source of commercial coir fiber (actually, a vascular strand) is the massive fibrous husk (3-5 cm thick) surrounding the coconut. This paper reports a SEM study of some aspects of this interesting fiber. The specimens were sputter coated with Au Pd and observed with 4 KV accelerating voltage.A cut cross section of a retted coir fiber is seen in Figures 1 and 2. A high degree of porosity is apparent; a core of the vascular or conductive bundle is seen surrounded by a large area of elongated sclerenchymatous cells which are cemented together into a composite with pectins or hemicelluloses.The sclerenchymatous cells may be separated by a maceration process, in this work a dilute solution of sodium hypochlorite. A bent, partially macerated coir fiber showing the configuration and orientation of the cells is given in Figure 3. A completely separated cell showing its general shape and pits is shown in a light photomicrograph in Figure 4.

scholarly journals Cross-section instability in financial markets: impatience, extrapolation, and switching

2021 ◽  
Author(s):  
Roberto Dieci ◽  
Xue-Zhong He
Keyword(s):  
Financial Markets ◽  
Cross Section ◽  
Asset Price ◽  
Asset Market ◽  
Long Run ◽  
Short Run ◽  
And Performance ◽  
Equilibrium Market ◽  
High Degree ◽  
Fundamental Price

AbstractThis paper presents a stylized model of interaction among boundedly rational heterogeneous agents in a multi-asset financial market to examine how agents’ impatience, extrapolation, and switching behaviors can affect cross-section market stability. Besides extrapolation and performance based switching between fundamental and extrapolative trading documented in single asset market, we show that a high degree of ‘impatience’ of agents who are ready to switch to more profitable trading strategy in the short run provides a further cross-section destabilizing mechanism. Though the ‘fundamental’ steady-state values, which reflect the standard present-value of the dividends, represent an unbiased equilibrium market outcome in the long run (to a certain extent), the price deviation from the fundamental price in one asset can spill-over to other assets, resulting in cross-section instability. Based on a (Neimark–Sacker) bifurcation analysis, we provide explicit conditions on how agents’ impatience, extrapolation, and switching can destabilize the market and result in a variety of short and long-run patterns for the cross-section asset price dynamics.

scholarly journals A possible radio signal of annihilating dark matter in the Abell 4038 cluster

2019 ◽  
Vol 495 (1) ◽  
pp. L124-L128 ◽  
Author(s):  
Man Ho Chan ◽  
Chak Man Lee
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Radio Signal ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Annihilation Cross Section ◽  
Radio Continuum ◽  
Test Statistic ◽  
Large Area ◽  
Dark Matter Annihilation

ABSTRACT In the past decade, some telescopes [e.g. Fermi-Large Area Telescope (LAT), Alpha Magnetic Spectrometer(AMS), and Dark Matter Particle Explorer(DAMPE)] were launched to detect the signals of annihilating dark matter in our Galaxy. Although some excess of gamma-rays, antiprotons, and electrons/positrons have been reported and claimed as dark matter signals, the uncertainties of Galactic pulsars’ contributions are still too large to confirm the claims. In this Letter, we report a possible radio signal of annihilating dark matter manifested in the archival radio continuum spectral data of the Abell 4038 cluster. By assuming the thermal annihilation cross-section and comparing the dark matter annihilation model with the null hypothesis (cosmic ray emission without dark matter annihilation), we get very large test statistic values >45 for four popular annihilation channels, which correspond to more than 6.5σ statistical preference. This provides a very strong evidence for the existence of annihilating dark matter. In particular, our results also support the recent claims of dark matter mass m ≈ 30–50 GeV annihilating via the bb̄ quark channel with the thermal annihilation cross-section.

scholarly journals Apical Extrusion of Debris Produced during Continuous Rotating and Reciprocating Motion

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Giselle Nevares ◽  
Felipe Xavier ◽  
Luciana Gominho ◽  
Flávia Cavalcanti ◽  
Marcely Cassimiro ◽  
...  
Keyword(s):  
Cross Section ◽  
Sodium Hypochlorite ◽  
Reciprocating Motion ◽  
Continuous Motion ◽  
Analytical Balance ◽  
Root Canals ◽  
Apical Extrusion ◽  
Final Weight ◽  
The Difference

This study aimed to analyse and compare apical extrusion of debris in canals instrumented with systems used in reciprocating and continuous motion. Sixty mandibular premolars were randomly divided into 3 groups (n=20): the Reciproc (REC), WaveOne (WO), and HyFlex CM (HYF) groups. One Eppendorf tube per tooth was weighed in advance on an analytical balance. The root canals were instrumented according to the manufacturer’s instructions, and standardised irrigation with 2.5% sodium hypochlorite was performed to a total volume of 9 mL. After instrumentation, the teeth were removed from the Eppendorf tubes and incubated at 37°C for 15 days to evaporate the liquid. The tubes were weighed again, and the difference between the initial and final weight was calculated to determine the weight of the debris. The data were statistically analysed using the Shapiro-Wilk, Wilcoxon, and Mann-Whitney tests (α=5%). All systems resulted in the apical extrusion of debris. Reciproc produced significantly more debris than WaveOne (p<0.05), and both systems produced a greater apical extrusion of debris than HyFlex CM (p<0.001). Cross section and motion influenced the results, despite tip standardization.

Turbulent buoyant convection from a source in a confined region

1969 ◽  
Vol 37 (1) ◽  
pp. 51-80 ◽  
Author(s):  
W. D. Baines ◽  
J. S. Turner
Keyword(s):  
Point Source ◽  
Cross Section ◽  
Laboratory Experiments ◽  
Region Of Interest ◽  
Constant Cross Section ◽  
General Shape ◽  
Turbulent Environment ◽  
Starting Conditions ◽  
Upward Velocity ◽  
Local Mean

This paper considers the effect of continuous convection from small sources of buoyancy on the properties of the environment when the region of interest is bounded. The main assumptions are that the entrainment into the turbulent buoyant region is at a rate proportional to the local mean upward velocity, and that the buoyant elements spread out at the top of the region and become part of the non-turbulent environment at that level. Asymptotic solutions, valid at large times, are obtained for the cases of plumes from point and line sources and also periodically released thermals. These all have the properties that the environment is stably stratified, with the density profile fixed in shape, changing at a uniform rate in time at all levels, and everywhere descending (with ascending buoyant elements).The analysis is carried out in detail for the point source in an environment of constant cross-section. Laboratory experiments have been conducted for this case, and these verify the major predictions of the theory. It is then shown how the method can be extended to include more realistic starting conditions for the convection, and a general shape of bounded environment. Finally, the model is applied quantitatively to a variety of problems in engineering, the atmosphere and the ocean, and the limitations on its use are discussed.

Large Area DPB Free (111) β-SiC Thick Layer Grown on (0001) α-SiC Nominal Surfaces by the CF-PVT Method

2005 ◽  
Vol 483-485 ◽  
pp. 225-228 ◽  
Author(s):  
Didier Chaussende ◽  
Laurence Latu-Romain ◽  
Laurent Auvray ◽  
M. Ucar ◽  
Michel Pons ◽  
...  
Keyword(s):  
Growth Rate ◽  
Optical Microscopy ◽  
Cross Section ◽  
Thick Layer ◽  
Vapour Transport ◽  
Large Area ◽  
Continuous Feed ◽  
Heating Up ◽  
Cross Section Geometry ◽  
Selection Of

Thick (111) oriented β-SiC layers have been grown by hetero-epitaxy on a (0001) a-SiC substrate with the Continuous Feed-Physical Vapour Transport (CF-PVT) method. The growth rate was 68 µm/h at a pressure of 2 torr and a temperature of 1950°C. The nucleation step of the β-SiC layer during the heating up of the process was studied in order to manage first the a to b heteropolytypic transition and second the selection of the b-SiC orientation. With a adapted seeding stage, we grew a 0.4mm thick layer almost free of Double Positioning Boundaries on a 30mm diameter sample. First observations of the layer by cross-polarised optical Microscopy are presented both in planar view and in cross section geometry.

scholarly journals Two-dimensional nanoframes with dual rims

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Sungjae Yoo ◽  
Jeongwon Kim ◽  
Sungwoo Choi ◽  
Doojae Park ◽  
Sungho Park
Keyword(s):  
Van Der Waals ◽  
Selective Etching ◽  
Van Der Waals Interactions ◽  
Two Dimensional ◽  
Large Area ◽  
Lattice Constants ◽  
Size And Shape ◽  
Single Entity ◽  
Synthetic Strategy ◽  
High Degree

AbstractThe synthesis of highly complex two-dimensional (2D) metal nanoframes remains a great challenge. Synthetic strategies for preparing 2D metal nanoframes are few, and rational and systematic synthetic pathways to more complicated architectures have not yet been reported. Herein, we demonstrate a stepwise synthetic strategy for complex 2D metal nanoframes with a high degree of intricacy; the strategy leads to a variety of shapes, including rings, triangles, hexagons, and tripods with tailorable single or double frames in a single entity. These nanoframes of high homogeneity could be obtained through selective combination of four different chemical toolkits consisting of selective etching and deposition on certain facets, and concentric and/or eccentric regrowth by controlling the mismatches of lattice constants of metals. The resulting nanoframes were highly homogeneous in size and shape and had van der Waals interactions that maximized rim-to-rim contact, allowing them to uniquely self-assemble into large-area superstructures.

scholarly journals Cyclic patterns in the central European tick-borne encephalitis incidence series

2016 ◽  
Vol 145 (2) ◽  
pp. 358-367 ◽  
Author(s):  
P. ZEMAN
Keyword(s):  
External Factors ◽  
Disease Dynamics ◽  
Large Area ◽  
Climatic Forcing ◽  
Human Contact ◽  
Cyclic Patterns ◽  
Tick Borne Encephalitis ◽  
Synchronization Signal ◽  
Phase Variations ◽  
High Degree

SUMMARYTick-borne encephalitis (TBE) is peculiar due to its unstable dynamics with profound inter-annual fluctuations in case numbers – a phenomenon not well understood to date. Possible reasons – apart from variable human contact with TBE foci – include external factors, e.g. climatic forcing, autonomous oscillations of the disease system itself, or a combined action of both. Spectral analysis of TBE data from six regions of central Europe (CE) revealed that the ostensibly chaotic dynamics can be explained in terms of four superposed (quasi-)periodical oscillations: a quasi-biennial, triennial, pentennial, and a decadal cycle. These oscillations exhibit a high degree of regularity and synchrony across CE. Nevertheless, some amplitude and phase variations are responsible for regional differences in incidence patterns. In addition, periodic changes occur in the degree of synchrony in the regions: marked in-phase periods alternate with rather off-phase periods. Such a feature in the disease dynamics implies that it arises as basically diverging self-oscillations of local disease systems which, at intervals, receive synchronizing impulses, such as periodic variations in food availability for key hosts driven by external factors. This makes the disease dynamics synchronized over a large area during peaks in the synchronization signal, shifting to asynchrony in the time in between.

High-Performance, Crimped Rayon Fiber

1976 ◽  
Vol 46 (3) ◽  
pp. 184-194 ◽  
Author(s):  
T. E. Muller ◽  
F. P. Barch ◽  
G. C. Daul
Keyword(s):  
Cross Section ◽  
High Performance ◽  
Full Range ◽  
High Strength ◽  
Cotton Fabrics ◽  
Textile Processing ◽  
Fiber Properties ◽  
Spin Bath ◽  
High Degree ◽  
Rayon Fiber

A high-wet-modulus crimped rayon fiber has been developed from a viscose system that utilizes a high-purity wood pulp, relatively low quantities of viscose modifiers, and viscose ripening controlled to allow the spinning of a highly-oriented rayon fiber with an unbalanced cross section. This results in a fiber which develops a high degree of both macro- and microcrimp. Viscose and spin-bath specifications must be rigidly observed, but spinning and fiber-relaxing conditions may be varied to adjust the development of crimp and fiber properties. This fiber performs well on conventional textile-processing equipment and can be spun into the full range of yarn counts that are normally defined by fiber denier. Resulting yarns have the high strength of the high-performance HWM rayons with the bulk and hand of cotton. Fabrics show better cover than that of similar fabrics woven from rayon control samples, and hand and dimensional stability are comparable to those of cotton. This fiber blends well with polyester and shows an advantage in cover over other rayon/polyester blends that are normally quite lean in appearance.

Etching Patterns of Sodium Hypochlorite Pretreated Hypocalcified Amelogenesis Imperfecta Primary Molars: SEM Study

2019 ◽  
Vol 43 (4) ◽  
pp. 257-262
Author(s):  
Amel Mahmoud Ahmed ◽  
Dina Nagy ◽  
Mona Abdallah Elkateb
Keyword(s):  
Phosphoric Acid ◽  
Sodium Hypochlorite ◽  
Amelogenesis Imperfecta ◽  
Acid Etching ◽  
Primary Molars ◽  
Control Group ◽  
Type I ◽  
Etching Pattern ◽  
Sem Study ◽  
Group Control Group

Aim: To investigate the etching patterns of hypocalcified amelogenesis imperfecta (AI) in primary molars pretreated with 5.25% NaOCl prior to phosphoric acid application using scanning electron microscopy (SEM). Study design: Ten hypocalcified AI primary molars were collected, sectioned longitudinally into 2 parts and allocated into two groups of ten specimens each. The enamel surface in the first group (control group) was etched using 37% phosphoric acid gel for 15 seconds; while in the second group (study group), it was pretreated using 5.25 sodium hypochlorite(NaOCl) for 60 seconds prior to acid etching. Each specimen was examined at 16 different sites, and evaluated for the etching pattern (types I, II, and III) distribution using SEM. A total of 320 microphotographs at 1,500 magnification were obtained using Auto-Cad 2007 software. Results: The etching pattern with phosphoric acid was not uniform with predominance of type III etching (65.63%), while the pretreated enamel surfaces showed a significant increase in type I and II(82.5%) etching patterns (P&lt;0.001). Conclusion: Treatment of primary teeth affected by hypocalcified AI using 5.25% NaOCl prior to phosphoric acid etching significantly improves the etching pattern which is required for good resin bonding.

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