scholarly journals The structure of the wall of the green alga Valonia ventricosa

1937 ◽  
Vol 122 (826) ◽  
pp. 76-97 ◽  
Keyword(s):  
Plant Cell Wall ◽  
Three Dimensional ◽  
Chain Structure ◽  
Point Of View ◽  
Considerable Importance ◽  
Yield Information ◽  
Degree Of Certainty ◽  
A Cell ◽  
Carry Over ◽  
Almost All

Although for many years the study of cytology has tended to concentrate attention more and more on the protoplast as the fundamental unit of the plant, there can be no doubt that the membrane surrounding this unit plays a part of considerable importance in its life processes. The deposition of such a membrane, by a process which is as yet quite obscure, is obviously closely connected with protoplasmic activity, and a detailed investigation of its structure is bound to lead to a better understanding of this connexion. At the same time, the shape and size of a cell are clearly due in some degree to the action of forces external and internal on the membrane, so that a study of the structure of the plant cell wall should therefore also yield information of considerable importance in the solution of botanical problems concerned with cell elongation and growth. Comparatively recent investigations, carried out chiefly on plant fibres, have shown that the most important component of cell walls, from a structural point of view, is the polysaccharide cellulose. This substance is known to occur in varying proportions in the walls of almost all plant tissue and its structure has been worked out, chiefly by X-ray and chemical methods, with some degree of certainty. Although much remains to be discovered of the organization of cellulose in the wall, certain details are now quite clear. Celluloses obtained from many and varied plant sources have all proved to have essentially the same structure. They exist only in the form of chains of β -glucose residues, at least 500 A long (Hengstenberg and Mark 1928), bound together laterally by secondary valences to form a three-dimensional lattice. The conception of a definite micelle, in the sense of Nägeli, is no longer widely held, although the lattice is not uniformly regular throughout the wall. The chains of cellulose are more probably bound together into ill-defined bundles separated by regions in which they are not so perfectly oriented. This conception of the existence of cellulose in long molecular chains has arisen from the examination of the secondary walls of plants, but as yet no direct experimental determinations have been possible of its structure in primary walls where it is known to occur ( e. g . in Vicia faba , see TupperCarey and Priestley 1922). Recent work (Preston 1934) on the tracheids of the conifer, however, show that it is possible to carry over the idea of the long-chain structure of cellulose even to these delicate primary walls.

Three-Dimensional Microfabrication System for Biodegradable Microdevices With High-Resolution and Bio-Applicability

2005 ◽  
Author(s):  
Akira Yamada ◽  
Fuminori Niikura ◽  
Koji Ikuta
Keyword(s):  
Tensile Strength ◽  
Biodegradable Polymers ◽  
Conventional Method ◽  
Three Dimensional ◽  
Single Layer ◽  
Batch Process ◽  
Potential Applications ◽  
A Cell ◽  
The One ◽  
Almost All

Biodegradable polymers are employed in medicine and its further application is expected with eagerness. But the lack of an appropriate processing method retards the progress. To overcome this problem, we have developped a novel three-dimensional microfabrication system. The system design allows us the processing of the free three-dimensional micro-level forms by stacking up melted polymers from the nozzle. Different from the conventional method, we adopted a batch process to supply materials in order to eliminate the prior process that required toxic solvents. In addition, it is possible to handle almost all biodegradable thermoplastic resins by adopting this system. A single layer from the piled-up layers of extruded lines was observed to evaluate the resolution. The lateral and depth resolutions attained are 40 μm and 45 μm, respectively. Biodegradable polymers enable three-dimensional microstructures such as micro-pipes, micro-bends, and micro-coil springs to be manufactured in less than 15 min. The biocompatibility of the newly fabricated structure was evaluated using a cell line (PC12). For this purpose, a small vessel, with a transparent base, was fabricated using PLA and cells were cultivated in it. The results were then compared with the results obtained using the standard method. The mechanical strength of our microstructures was evaluated using a tensile strength test. The tensile strength of the microstructure was lower than the one obtained from the conventional method, but has enough strength for fabrication of medical devices. Our system renders it possible to produce toxic-free, as well as transparent and leakage-free devices. Our system is expected to have potential applications in optimum design and fabrication of implantable devices, especially in tissue engineering.

Tree Pattern Matching

1997 ◽  
Author(s):  
K. Zhang ◽  
D. Shasha
Keyword(s):  
Point Of View ◽  
Programming Approach ◽  
Suffix Trees ◽  
Dynamic Programming Approach ◽  
Ordered Trees ◽  
Single Leaf ◽  
Tree Pattern Matching ◽  
A Cell ◽  
Carry Over ◽  
Don't Cares

Most of this book is about stringology, the study of strings. So why this chapter on trees? Why not graphs or geometry or something else? First, trees generalize strings in a very direct sense: a string is simply a tree with a single leaf. This has the unsurprising consequence that many of our algorithms specialize to strings and the happy consequence that some of those algorithms are as efficient as the best string algorithms. From the point of view of “treeology”, there is the additional pragmatic advantage of this relationship between trees and strings: some techniques from strings carry over to trees, e.g., suffix trees, and others show promise though we don’t know of work that exploits it. So, treeology provides a good example area for applications of stringologic techniques. Second, some of our friends in stringology may wonder whether there is some easy reduction that can take any tree edit problem, map it to strings, solve it in the string domain and then map it back. We don’t believe there is, because, as you will see, tree editing seems inherently to have more data dependence than string editing. (Specifically, the dynamic programming approach to string editing is always a local operation depending on the left, upper, and upper left neighbor of a cell. In tree editing, the upper left neighbor is usually irrelevant — instead the relevant cell depends on the tree topology.) That is a belief not a theorem, so we would like to state right at the outset the key open problem of treeology: can all tree edit problems on ordered trees (trees where the order among the siblings matters) be reduced efficiently to string edit problems and back again?. The rest of this chapter proceeds on the assumption that this question has a negative response. In particular, we discuss the best known algorithms for tree editing and several variations having to do with subtree removal, variable length don’t cares, and alignment. We discuss both sequential and parallel algorithms.

scholarly journals Breed-and-burn fuel cycle in molten salt reactors

2019 ◽  
Vol 5 ◽  
pp. 15 ◽  
Author(s):  
Boris Hombourger ◽  
Jiři Křepel ◽  
Andreas Pautz
Keyword(s):  
Molten Salt ◽  
Fuel Cycle ◽  
Three Dimensional ◽  
Point Of View ◽  
Cell Level ◽  
Neutron Excess ◽  
Breed And Burn ◽  
A Cell ◽  
The Cost ◽  
Fast Spectrum Reactors

The operation of a reactor on an open but self-sustainable cycle without actinide separation is known as breed-and-burn. It has mostly been envisioned for use in solid-fueled fast-spectrum reactors such as sodium-cooled fast reactors. In this paper the applicability of breed-and-burn to molten salt reactors is investigated first on a cell level using a modified neutron excess method. Several candidate fuel salts are selected and their performance in a conceptual three-dimensional reactor is investigated. Chloride-fueled single-fluid breed-and-burn molten salt reactors using enriched chlorine are shown to be feasible from a neutronics and fuel cycle point of view at the cost of large fuel inventories.

scholarly journals The biomaterialist’s task: scaffold biomaterials and fabrication technologies

Joints ◽  
2013 ◽  
Vol 01 (03) ◽  
pp. 130-137 ◽  
Author(s):  
Francesca Gervaso ◽  
Alessandro Sannino ◽  
Giuseppe Peretti
Keyword(s):  
Three Dimensional ◽  
Point Of View ◽  
Cell Selection ◽  
Cell Seeding ◽  
A Cell ◽  
Engineered Tissue ◽  
Dimensional Cell ◽  
Cell Support ◽  
Key Questions ◽  
The Ideal

This paper focuses on tissue engineering (TE) from the biomaterialist’s point of view. With the aim of answering some simple but key questions about TE, the related literature is here reviewed. In order to obtain an engineered tissue the following steps are mandatory: (a) cell selection, (b) identification of the ideal three-dimensional scaffold for cell seeding and proliferation, (c) choice of the most suitable type of cell culture. Whereas the biotechnologist working in the TE field is responsible for optimizing the cell seeding and culture, the biomaterialist has the challenging task of optimizing the three-dimensional cell support, or scaffold. Therefore, in the present paper, scaffold properties, biomaterials and fabrication technologies are analyzed in depth and reviewed on the basis of the current literature. Finally, mention is also made of the most recently emerging and innovative technologies relating to scaffolds for TE applications.

2. French Retrospect

1882 ◽  
Vol 28 (122) ◽  
pp. 279-283
Author(s):  
W. Herbert Packer
Keyword(s):  
Point Of View ◽  
Considerable Importance ◽  
Moral Treatment ◽  
Powerful Effect ◽  
Folie À Deux ◽  
Almost All ◽  
Folie A Deux

The following translation of a letter in the “Progrès Medical” of the 2nd July, 1881, seems to me of considerable interest as showing, among other things, the powerful effect of the force of imitation in that Protean disease hysteria, and also the result of bad moral treatment. A series of somewhat similar cases, illustrating what has been well called the contagion of nervous affections in these leading to undoubted insanity with distinct delusions, is well described, and typical cases noted, by Dr. M. de Montgel, of the Marseilles Public Asylum, in the January number of the “Annales-Medico-Psychologiques.” But in almost all the cases there cited hereditary taint was distinctly made out, the weak mind being crushed by continued contact with the insane one. This folie-à-deux deserves serious attention; it may, from a medico-legal point of view, assume considerable importance; for instance, a person accused of crime may be under the domination of another's delusions. Many of the ecstatic outbreaks of seeming religion exemplify this form of insanity, often observed although seldom treated according to their deserts.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

scholarly journals 3D Reconstruction of Cultural Heritage Sites as an Educational Approach. The Sanctuary of Delphi

2021 ◽  
Vol 11 (8) ◽  
pp. 3635
Author(s):  
Ioannis Liritzis ◽  
Pantelis Volonakis ◽  
Spyros Vosinakis
Keyword(s):  
University Students ◽  
3D Reconstruction ◽  
Cultural Heritage ◽  
New Technology ◽  
Three Dimensional ◽  
Computer Gaming ◽  
Educational Approach ◽  
Heritage Sites ◽  
3D Environment ◽  
Almost All

In the field of cultural heritage, three-dimensional (3D) reconstruction of monuments is a usual activity for many professionals. The aim in this paper focuses on the new technology educational application combining science, history, and archaeology. Being involved in almost all stages of implementation steps and assessing the level of participation, university students use tools of computer gaming platform and participate in ways of planning the virtual environment which improves their education through e-Learning. The virtual 3D environment is made with different imaging methods (helium-filled balloon, Structure for motion, 3D repository models) and a developmental plan has been designed for use in many future applications. Digital tools were used with 3D reconstructed buildings from the museum archive to Unity 3D for the design. The pilot study of Information Technology work has been employed to introduce cultural heritage and archaeology to university syllabuses. It included students with a questionnaire which has been evaluated accordingly. As a result, the university students were inspired to immerse themselves into the virtual lab, aiming to increasing the level of interaction. The results show a satisfactory learning outcome by an easy to use and real 3D environment, a step forward to fill in needs of contemporary online sustainable learning demands.

scholarly journals Functional Assessment of 12 Rare Allelic CYP2C9 Variants Identified in a Population of 4773 Japanese Individuals

2021 ◽  
Vol 11 (2) ◽  
pp. 94
Author(s):  
Masaki Kumondai ◽  
Akio Ito ◽  
Evelyn Marie Gutiérrez Rico ◽  
Eiji Hishinuma ◽  
Akiko Ueda ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Three Dimensional ◽  
Warfarin Dose ◽  
Catalytic Efficiency ◽  
Therapeutic Window ◽  
Wild Type ◽  
Drug Metabolizing Enzyme ◽  
Novel Variants ◽  
Metabolizing Enzyme ◽  
Almost All

Cytochrome P450 2C9 (CYP2C9) is an important drug-metabolizing enzyme that contributes to the metabolism of approximately 15% of clinically used drugs, including warfarin, which is known for its narrow therapeutic window. Interindividual differences in CYP2C9 enzymatic activity caused by CYP2C9 genetic polymorphisms lead to inconsistent treatment responses in patients. Thus, in this study, we characterized the functional differences in CYP2C9 wild-type (CYP2C9.1), CYP2C9.2, CYP2C9.3, and 12 rare novel variants identified in 4773 Japanese individuals. These CYP2C9 variants were heterologously expressed in 293FT cells, and the kinetic parameters (Km, kcat, Vmax, catalytic efficiency, and CLint) of (S)-warfarin 7-hydroxylation and tolbutamide 4-hydroxylation were estimated. From this analysis, almost all novel CYP2C9 variants showed significantly reduced or null enzymatic activity compared with that of the CYP2C9 wild-type. A strong correlation was found in catalytic efficiencies between (S)-warfarin 7-hydroxylation and tolbutamide 4-hydroxylation among all studied CYP2C9 variants. The causes of the observed perturbation in enzyme activity were evaluated by three-dimensional structural modeling. Our findings could clarify a part of discrepancies among genotype–phenotype associations based on the novel CYP2C9 rare allelic variants and could, therefore, improve personalized medicine, including the selection of the appropriate warfarin dose.

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