scholarly journals Is the orientation of the fibrillar helix in the main layer of cell walls constant or variable within a tree?

2015 ◽  
Vol 41 (1) ◽  
pp. 27-38
Author(s):  
W. Pyszyński ◽  
Z. Hejnowicz
Keyword(s):  
Cell Walls ◽  
General Trend ◽  
Abies Alba ◽  
The Other ◽  
Cell Axis ◽  
Main Layer ◽  
Study Material ◽  
A Cell ◽  
Wood Grain ◽  
Picea Excelsa

The study material consisted of samples from 270 <i>Picea excelsa</i> and 54 <i>Abies alba</i> trees with variable type of wood grain. No correlation was found between the orientation of the fibrils and the type of grain. In all the samples in which the fibrillar helix formed an angle with the cell axis greater than 10° (80% of the total) the helix was of Z type. In the other samples undulations commonly occured in the orientation of fibrils within a cell. These were in the form of local deviations to the left or right of the general trend to develop the Z type of spiral.

Influence of grain direction in vibrational wood welding

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 23-27 ◽  
Author(s):  
Milena Properzi ◽  
Jean-Michel Leban ◽  
Antonio Pizzi ◽  
Stephanie Wieland ◽  
Frederic Pichelin ◽  
...  
Keyword(s):  
Cell Walls ◽  
Grain Orientation ◽  
Marked Effect ◽  
Fibre Orientation ◽  
The Other ◽  
Matrix Composites ◽  
Lower Strength ◽  
Wood Grain ◽  
Strength Result ◽  
Fibre Matrix

Abstract Wood grain orientation differences in the two surfaces to be bonded yield bondlines of different strength in no-adhesives wood welding. Longitudinal wood grain bonding of tangential and radial wood sections yields an approximately 10% difference in strength results of the joint. Cross-grain (±90°) bonding yields instead a much lower strength result, roughly half that observed for pieces bonded with the grain parallel to each other. These differences can be explained by the very marked effect that homogeneity of fibre orientation is known to have on fibre–matrix composites. Oak yields lower results than beech and maple and is more sensitive to welding conditions. Differences in both anatomical and wood constituent composition can account for this difference in performance. Contrary to the other wood species, oak always presents joint bondlines where little or no increase in density at the interface is noticed. This explains its somewhat lower strength results. This is based on the different mode of bonding predominant in this species, while the other species present two different modes of bonding. Thus, two types of bondlines are observed by scanning electron microscopy (SEM): (i) bondlines where entangled fibre–matrix composites are formed at the interface and (ii) bondlines in which direct welding of the cell walls occurs, just by fused intercellular material or cell surface material. In this latter case the cells remain flat, without an entangled fibre–matrix composite being formed. This is the almost exclusively predominant case for oak. Both cases and even hybrid cases between the two have also been observed in beech.

Toxæmia in the Etiology of Mental Disease. a Discussion opened

1902 ◽  
Vol 48 (202) ◽  
pp. 434-450 ◽  
Author(s):  
T. S. Clouston
Keyword(s):  
Nerve Cell ◽  
General Trend ◽  
Mental Disease ◽  
The Other ◽  
British Association ◽  
Younger Men ◽  
Full Knowledge ◽  
The Subject ◽  
Definition Of ◽  
Do So

Dr. Clouston said that when he suggested toxæmia to the secretary as a suitable subject for a discussion at this meeting he had not intended to be the first speaker, because his object was to bring out more fully the views of the younger members who had recently committed themselves so strongly to the toxæmic and bacterial etiology of insanity, and so to get light thrown on some of the difficulties which he and others had felt in applying this theory to many of their cases in practice. It was not that he did not believe in the toxic theory as explaining the onset of many cases, or that he under-rated its importance, but that he could not see how it applied so universally or generally as some of the modern pathological school were now inclined to insist on. He knew that it was difficult for those of the older psychological and clinical school to approach the subject with that full knowledge of recent bacteriological and pathological doctrine which the younger men possessed, or to breathe that all-pervading pathological atmosphere which they seemed to inhale. He desired to conduct this discussion in an absolutely non-controversial and purely scientific spirit. To do so he thought it best to put his facts, objections, and difficulties in a series of propositions which could be answered and explained by the other side. He thought it important to define toxæmia, but should be willing to accept Dr. Ford Robertson's definition of toxines, viz., “Substances which are taken up by the (cortical nerve) cell and then disorder its metabolism.” He took the following extracts from his address at the Cheltenham meeting of the British Association (1) as representing Dr. Ford Robertson's views and the general trend of much investigation and hypothesis on the Continent.

scholarly journals MICRURGICAL STUDIES IN CELL PHYSIOLOGY

1926 ◽  
Vol 10 (1) ◽  
pp. 9-21 ◽  
Author(s):  
Paul Reznikoff
Keyword(s):  
Heavy Metals ◽  
Metal Cation ◽  
Surface Membrane ◽  
The Other ◽  
Contractile Vacuole ◽  
Toxic Action ◽  
Cell Physiology ◽  
Relative Toxicity ◽  
A Cell

I. Plasmalemma. 1. The order of toxicity of the salts used in these experiments on the surface membrane of a cell, taking as a criterion viability of amebæ immersed in solutions for 1 day, is HgCl2, FeCl3&gt; AlCl3&gt; CuCl2&gt; PbCl2&gt; FeCl2. Using viability for 5 days as a criterion, the order of toxicity is PbCl2&gt; CuCl2&gt; HgCl2&gt; AlCl3&gt; FeCl3&gt; FeCl2. 2. The rate of toxicity is in the order FeCl3&gt; HgCl2&gt; AlCl3&gt; FeCl2&gt; CuCl2&gt; PbCl2. 3. The ability of amebæ to recover from a marked tear of the plasmalemma in the solutions of the salts occurred in the following order: AlCl3&gt; PbCl2&gt; FeCl2&gt; CuCl2&gt; FeCl3&gt; HgCl2. II. Internal Protoplasm. 4. The relative toxicity of the salts on the internal protoplasm, judged by the recovery of the amebæ from large injections and the range over which these salts can cause coagulation of the internal protoplasm, is in the following order: PbCl2&gt; CuCl2&gt; FeCl3&gt; HgCl2&gt; FeCl2&gt; AlCl3. 5. AlCl3 in concentrations between M/32 and M/250 causes a marked temporary enlargement of the contractile vacuole. FeCl2, FeCl3, and CuCl3 produce a slight enlargement of the vacuole. 6. PbCl2, in concentrations used in these experiments, appears to form a different type of combination with the internal protoplasm than do the other salts. III. Permeability. 7. Using the similarity in appearance of the internal protoplasm after injection and after immersion to indicate that the surface is permeable to a substance in which the ameba is immersed, it is concluded that AlCl3 can easily penetrate the intact plasmalemma. CuCl2 also seems to have some penetrating power. None of the other salts studied give visible internal evidence of penetrability into the ameba. IV. Toxicity. 8. The toxic action of the chlorides of the heavy metals used in these experiments, and of aluminum, is exerted principally upon the surface of the cell and is due not only to the action of the metal cation but also to acid which is produced by hydrolysis.

scholarly journals CULTURAL REPRESENTATION OF POWER AND THE COURT DURING THE PERSONAL REIGN OF CHARLES I STUART

2020 ◽  
Vol 30 (1) ◽  
pp. 104-110
Author(s):  
L. I. Ivonina
Keyword(s):  
Social Context ◽  
General Trend ◽  
Daily Life ◽  
Cultural Representation ◽  
The Other ◽  
Charles I ◽  
The World ◽  
King Charles I ◽  
History Of ◽  
The One

The article analyzes the main features of the Caroline era in the history of Britain, which were reflected in the cultural representation of the power of King Charles I Stuart and the court’s daily life in the 1630s. The author shows that, on the one hand, the cult of peace and the greatness of the monarch were the cultural product of the Caroline court against the background of the Thirty Years' War in continental Europe. On the other hand, there was a spread of various forms of escapism, the departure into the world of illusions. On the whole, the representation of the power of Charles Stuart and the court’s daily life were in line with the general trend of the time. At the same time, the court of Charles I reflected his personality. Thinly sensing and even determining the artistic tastes of his era, the English king abstracted from its political and social context.

scholarly journals Organismal view of a plant and a plant cell.

2001 ◽  
Vol 48 (2) ◽  
pp. 443-451 ◽  
Author(s):  
P Wojtaszek
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Cell Walls ◽  
Growth Time ◽  
Dead Cell ◽  
Plant Body ◽  
The Status ◽  
A Cell ◽  
Plant Form ◽  
Biological Organisation

Cell walls are at the basis of a structural, four-dimensional framework of plant form and growth time. Recent rapid progress of cell wall research has led to the situation where the old, long-lasting juxtaposition: "living" protoplast--"dead" cell wall, had to be dropped. Various attempts of re-interpretation cast, however, some doubts over the very nature of plant cell and the status of the walls within such a cell. Following a comparison of exocellular matrices of plants and animals, their position in relation to cells and organisms is analysed. A multitude of perspectives of the biological organisation of living beings is presented with particular attention paid to the cellular and organismal theories. Basic tenets and resulting corollaries of both theories are compared, and evolutionary and developmental implications are considered. Based on these data, "The Plant Body"--an organismal concept of plants and plant cells is described.

scholarly journals Numerical Simulation of a Textured and Untextured Photovoltaic Solar Cell: Comparative study

2021 ◽  
Vol 03 (01) ◽  
pp. 104-114
Author(s):  
Karim Salim ◽  
◽  
M.N Amroun ◽  
K Sahraoui ◽  
W Azzoui ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Solar Cell ◽  
Comparative Study ◽  
Silicon Solar Cell ◽  
The Other ◽  
Surface Parameters ◽  
Cell Efficiency ◽  
Photovoltaic Solar Cell ◽  
A Cell

Increasing the efficiency of solar cells relies on the surface of the solar cell. In this work, we simulated a textured silicon solar cell. This simulation allowed us to predict the values of the surface parameters such as the angle and depth between the pyramids for an optimal photovoltaic conversion where we found the Icc: 1.783 (A) and Vco: 0.551 (V) with a cell efficiency of about 13.56%. On the other hand, we performed another simulation of a non-textured solar cell to compare our values and found Icc: 1.623 (A) and Vco: 0.556 (V) with an efficiency of about 12.76%.

scholarly journals I Like Vegetables: A Touch-and-Feel Board Book by L. Siminovich

2011 ◽  
Vol 1 (1) ◽  
Author(s):  
Kim Frail
Keyword(s):  
Cross Section ◽  
Public Services ◽  
Picture Book ◽  
The Other ◽  
Learning Method ◽  
University Of Alberta ◽  
Young Readers ◽  
Dinner Table ◽  
Wood Grain ◽  
The University

Siminovich, Lorena. I Like Vegetables: A Touch-and-Feel Board Book. Somerville: Candlewick Press, 2011. Print.“I Like Vegetables” is a dream come true for any nutritionally conscience parent, children’s librarian or teacher. The brightly hued collage illustrations are intriguingly textured with patterns and “touch & feel” inlays. Silky peas and rough-skinned carrots invite young readers to learn about vegetables. The layout is quite clever as it leverages contrast and comparison as a learning method. On one side of the page vegetables are depicted as they would appear growing in the garden while on the other side they are in the home being prepared for the dinner table. In addition, the nature side of the page illustrates the concept of opposites. For example, there are “tall” and “short” cornstalks. Orange carrot roots are “below” the ground, while the feathery green tops are “above”. The indoor side of the page features close-ups of vegetables against a wood-grain background that evokes a cutting board. Here children get a different perspective on the harvested veggies. We see shelled peas, open cornhusks and a cross-section of a pumpkin. The concluding series of images features an “empty” gardener’s basket next to a basket “full” of colourful vegetables on a blue and white gingham picnic tablecloth inlay.  This is primarily a picture book with only the names of the vegetables and the two opposing concepts appearing on each page. The typeset is Helvetica and is large and easy to read.  It is a sturdy board book and the inlays could not be easily ripped out or damaged. It is therefore a welcome addition to any toddler’s library. Other titles in the “I Like” series by Siminovich include: “I Like Toys “, “I Like Bugs” and “I Like Fruit”. “I Like Vegetables” is sure to engage children from ages 1-3. Highly recommended: 4 out of 4 stars Reviewer: Kim FrailKim is a Public Services Librarian at the H.T. Coutts Education Library at the University of Alberta. Children’s literature is a big part of her world at work and at home. She also enjoys gardening, renovating and keeping up with her two-year old. 

scholarly journals Secretion of Cryparin, a Fungal Hydrophobin

1999 ◽  
Vol 65 (12) ◽  
pp. 5431-5435 ◽  
Author(s):  
Patricia M. McCabe ◽  
Neal K. Van Alfen
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Submerged Culture ◽  
Secretory Pathway ◽  
Culture Medium ◽  
Secretory Vesicle ◽  
Cryphonectria Parasitica ◽  
Secreted Protein ◽  
Filamentous Ascomycete ◽  
A Cell

ABSTRACT Cryparin is a cell-surface-associated hydrophobin of the filamentous ascomycete Cryphonectria parasitica. This protein contains a signal peptide that directs it to the vesicle-mediated secretory pathway. We detected a glycosylated form of cryparin in a secretory vesicle fraction, but secreted forms of this protein are not glycosylated. This glycosylation occurred in the proprotein region, which is cleaved during maturation by a Kex2-like serine protease, leaving a mature form of cryparin that could be isolated from both the cell wall and culture medium. Pulse-chase labeling experiments showed that cryparin was secreted through the cell wall, without being bound, into the culture medium. The secreted protein then binds to the cell walls ofC. parasitica, where it remains. Binding of cryparin to the cell wall occurred in submerged culture, presumably because of the lectin-like properties unique to this hydrophobin. Thus, the binding of this hydrophobin to the cell wall is different from that of other hydrophobins which are reported to require a hydrophobic-hydrophilic interface for assembly.

COMPARISON OF INTACT, LATE-CASTRATED, AND DIETHYLSTILBESTROL (DES)-IMPLANTED BOARS WITH BARROWS AND GILTS: NITROGEN AND ENERGY DIGESTIBILITY, NITROGEN RETENTION, CARCASS MEASUREMENTS, MUSCLE ANALYSES, AND RESIDUAL DES IN MUSCLE TISSUE

1973 ◽  
Vol 53 (3) ◽  
pp. 579-585 ◽  
Author(s):  
J. A. NEWELL ◽  
J. P. BOWLAND
Keyword(s):  
Muscle Tissue ◽  
Dry Matter ◽  
General Trend ◽  
Nitrogen Retention ◽  
Carcass Characteristics ◽  
Ash Content ◽  
Metabolizable Energy ◽  
The Other ◽  
Average Weight ◽  
Grade Index

Forty boars, eight barrows, and eight gilts were allotted in groups of four pigs each at an average weight of 13.1 kg. Metabolism studies with a portion of the animals were conducted at 15 and 50 kg liveweight. Although no statistical differences between sexes were found in these studies, barrows tended to digest more nitrogen (N) but to retain less than boars and gilts. N digestibility (DN) and retention (NR) values at 50 kg were higher than those at 15 kg. The three sexes were found to be similar in energy digestibility (DE) and metabolizable energy (ME). Significant differences were found for boars in DE and ME coefficients between the two periods, averaging 83.2 and 85.6% DE in the 15- and 50-kg periods, respectively. At 70 kg, 16 boars were implanted with 96 mg of diethylstilbestrol (DES), 16 boars were castrated, and 8 boars were left intact. Barrows had thicker backfat (P < 0.05) and lower (P < 0.05) grade index than any of the other treatments. Late-castrated boars showed a general trend to revert to the carcass characteristics of barrows but were still superior to barrows at market weight. No significant differences between treatments were found for dry matter, protein, fat, or ash content of the longissimus muscle. No residual DES was found in the muscle tissue of the implanted boars.

Tandem Conveyor Queues

1989 ◽  
Vol 3 (4) ◽  
pp. 517-536
Author(s):  
F. Baccelli ◽  
E.G. Coffman ◽  
E.N. Gilbert
Keyword(s):  
Boundary Value Problem ◽  
Joint Distribution ◽  
Queueing System ◽  
The Other ◽  
Riemann Boundary Value Problem ◽  
Riemann Boundary ◽  
Special Cases ◽  
A Cell ◽  
Service Times ◽  
Input Position

This paper analyzes a queueing system in which a constant-speed conveyor brings new items for service and carries away served items. The conveyor is a sequence of cells each able to hold at most one item. At each integer time, a new cell appears at the queue's input position. This cell holds an item requiring service with probability a, holds a passerby requiring no service with probability b, and is empty with probability (1– a – b). Service times are integers synchronized with the arrival of cells at the input, and they are geometrically distributed with parameter μ. Items requiring service are placed in an unbounded queue to await service. Served items are put in a second unbounded queue to await replacement on the conveyor in cells at the input position. Two models are considered. In one, a served item can only be placed into a cell that was empty on arrival; in the other, the served item can be placed into a cell that was either empty or contained an item requiring service (in the latter case unloading and loading at the input position can take place in the same time unit). The stationary joint distribution of the numbers of items in the two queues is studied for both models. It is verified that, in general, this distribution does not have a product form. Explicit results are worked out for special cases, e.g., when b = 0, and when all service times are one time unit (μ = 1). It is shown how the analysis of the general problem can be reduced to the solution of a Riemann boundary-value problem.

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