scholarly journals Optimization of the binding of dissociated exfoliated cervico-vaginal cells to glass microscope slides.

1977 ◽  
Vol 25 (7) ◽  
pp. 538-543 ◽  
Author(s):  
R C Leif ◽  
D Ingram ◽  
C Clay ◽  
D Bobbitt ◽  
R Gaddis ◽  
...  
Keyword(s):  
The Other ◽  
Centrifugal Field ◽  
Bonding Agents ◽  
Cell Dissociation ◽  
Silicone Coating ◽  
Glass Slides ◽  
Acceleration And Deceleration ◽  
A Cell ◽  
Microscope Slides ◽  
Glass Microscope

In order to monitor the development of a cell dissociation technique, it was essential to utilize the Centrifugal Cytology rotor to produce glutaraldehyde-fixed even cellular dispersions. The Cytology rotor has been improved to insure rapid alignment with the centrifugal field during both acceleration and deceleration, and the fixative is now delivered to the surface of the slide. The dissociation of the cells results in a loss of their adhesion to glass slides. Three bonding agents were tested: (a) Poly-L-Lysine; (b) Mayer's albumin fixative; (c) positively charging the slides with a silicone coating. The results with 65% albumin-coated slides were clearly superior to the other two. The addition of a postfixation step of 95% ethanol/4% polyethylene glycol did not significantly affect the recovery of the cells, but did eliminate some unevenness in the Centrifugal Cytology preparations, flattened the cells and expedited the procedure.

Epitasis and Anesis in Aristotle, De caelo 2.6

Phronesis ◽  
2016 ◽  
Vol 61 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Stephen E. Kidd
Keyword(s):  
The Other ◽  
Irregular Motion ◽  
Acceleration And Deceleration ◽  
The One

De caelo 2.6 describes irregular motion differently from the discussion at Physics 5.4. The desire to make the one discussion congrue with the other has strained interpretation of the De caelo passage. Aristotle provides a theory of irregular motion that is tripartite and the passage ought to be interpreted in such a way as to explain this tripartite motion. Akmē is not a ‘top speed’ as it is generally translated, but a point in an object’s motion when epitasis must become anesis. Although the terms epitasis and anesis cover ‘acceleration’ and ‘deceleration’ they cannot be reduced to them.

The disposition of benzo(a)pyrene in the periphyton communities of two South Carolina streams: uptake and biotransformation

1982 ◽  
Vol 60 (10) ◽  
pp. 2084-2091 ◽  
Author(s):  
Mary G. Bruno ◽  
Timothy E. Fannin ◽  
Gordon J. Leversee
Keyword(s):  
South Carolina ◽  
Slide Surface ◽  
Uptake Rates ◽  
Area Basis ◽  
Autoradiographic Analysis ◽  
Colonization Time ◽  
Microscope Slides ◽  
Surface Area Basis ◽  
Glass Microscope ◽  
Sheath Material

The effect of periphyton community composition and colonization time on the uptake and biotransformation of benzo(a)pyrene (BaP) was determined in laboratory studies. Naturally colonized glass microscope slides were collected after 3 and 6 weeks from Castor Creek, which has a predominantly desmid flora, and after 3 and 5 weeks from diatom-dominated Upper Three Runs Creek. When expressed on a slide surface-area basis, the Castor Creek periphyton showed significantly greater BaP uptake rates at both colonization periods. Within streams, uptake rates increased significantly with colonization time. Autoradiographic analysis suggests that BaP was accumulated by surface sorption, especially to gelatinous sheath material. Active biotransformation as measured by the percentage extractable non-BaP 14C was not detected in either community.

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> AlCl3> CuCl2> PbCl2> FeCl2. Using viability for 5 days as a criterion, the order of toxicity is PbCl2> CuCl2> HgCl2> AlCl3> FeCl3> FeCl2. 2. The rate of toxicity is in the order FeCl3> HgCl2> AlCl3> FeCl2> CuCl2> 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> PbCl2> FeCl2> CuCl2> FeCl3> 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> CuCl2> FeCl3> HgCl2> FeCl2> 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 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%.

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.

Analyse de la morphogenèse du pied des Oiseaux à l'aide de mélanges cellulaires interspécifiques

Development ◽  
1973 ◽  
Vol 29 (1) ◽  
pp. 175-196
Author(s):  
Par Marie-Paule Pautou
Keyword(s):  
Cell Suspension ◽  
The Other ◽  
Composite Type ◽  
A Cell ◽  
Species Specific ◽  
Host Embryo

Morphogenesis of the feet of birds, studied in limbs developed from reaggregated heterospecific mesoderm Experiments were undertaken to determine whether species-specific characters of chick and duck mesodermal leg-bud cells are retained after dissociation and reaggregation in homoand heterospecific mixtures. Prospective zeugopod and autopod mesoderm from chick and/or duck leg buds were isolated, dissociated into a cell suspension and pelleted by centrifugation. The reaggregated mesoderm was packed into a leg-bud ectodermal jacket; the recombined leg bud was then grafted on the wing stump of a host embryo. Recombinants whose mesoderm was a homospecific reaggregate developed into typical chick or duck leg parts according to the specific origin of the mesodermal component; the feet of nearly all these legs lacked antero-posterior polarity. Recombinants containing heterospecific reaggregates were also capable of forming reasonably organized leg structures. The foot was not, as a rule, of the specific type expected of the majority component. In a mixture of 75% chick mesoderm cells and 25% duck mesoderm cells, the feet which developed were either of chick type or of composite chick/duck type, where typical chick areas were next to typical or aberrant (steganoid) duck areas. When the ratio was reversed (25% chick, 75% duck), the majority of the feet were again of chick type or of composite chick/duck type, the typical duck phenotype being exceptional. Even in a mixture of 10% chick cells and 90% duck cells, duck-type feet were not obtained. They were all of composite type: half of their interdigital zones were of chick type, the other half were occupied, in most cases, by underdeveloped, indented webbing or by one or several discrete flaps, and, in a few cases, by normal webbing. The vast majority of the feet developed from heterospecific mesoderm were characterized by the profusion of the toes, which were not polarized along the a–p axis.

Establishment of gut fate in the E lineage of C. elegans: the roles of lineage-dependent mechanisms and cell interactions

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1267-1277 ◽  
Author(s):  
B. Goldstein
Keyword(s):  
Cell Interactions ◽  
The Other ◽  
Cell Contact ◽  
Cell Stage ◽  
C Elegans ◽  
Daughter Cells ◽  
Intact Embryo ◽  
A Cell ◽  
Random Position ◽  
Recombination Experiments

The gut of C. elegans derives from all the progeny of the E blastomere, a cell of the eight cell stage. Previous work has shown that gut specification requires an induction during the four cell stage (Goldstein, B. (1992) Nature 357, 255–257). Blastomere isolation and recombination experiments were done to determine which parts of the embryo can respond to gut induction. Normally only the posterior side of the EMS blastomere contacts the inducing cell, P2. When P2 was instead placed in a random position on an isolated EMS, gut consistently differentiated from the daughter of EMS contacting P2, indicating that any side of EMS can respond to gut induction. Additionally, moving P2 around to the opposite side of EMS in an otherwise intact embryo caused EMS's two daughter cells to switch lineage timings, and gut to differentiate from the descendents of what normally would be the MS blastomere. The other cells of the four cell stage, ABa, ABp, and P2, did not form gut when placed in contact with the inducer. To determine whether any other inductions are involved in gut specification, timed blastomere isolations were done at the two and eight cell stages. In the absence of cell contact at the two cell stage, segregation of gut fate proceeded normally at both the two and four cell stages. Gut fate also segregated properly in the absence of cell contact at the eight cell stage. A model is presented for the roles of lineage-dependent mechanisms and cell interactions in establishing gut fate in the E lineage.

Predicting the Chemistry Inside a Cell

2016 ◽  
Author(s):  
Ben McFarland
Keyword(s):  
Scientific Discovery ◽  
The Other ◽  
The South ◽  
Google Maps ◽  
The North ◽  
Closed Circle ◽  
Stone Wall ◽  
Small Stone ◽  
A Cell ◽  
Hadrian's Wall

The process of scientific discovery is something like a walk near Freswick Castle. I assume you’ve never been there. (Neither have I, but a friend has.) Freswick Castle stands at the end of Scotland’s northeast end, at the mouth of the Burn of Freswick in the district of Caithness. As of this writing, it is unlisted in Google Maps, and I had to manually scan the coast to find it. Outside the castle is a simple, unlabeled structure that doubles as a biochemical parable. The castle itself is narrow and three stories tall, with orange shingles and gray stone, set on an arc of narrow beach between hills to the north and cliffs to the south. The building is approximately the cruciform shape of a shrunken cathedral, with the rightward wing moved to the top of the structure so it resembles a lowercase f. If you wander the grounds near Freswick Castle, you will discover a stone wall in the wind-blown waves of yellow- green grass, worn but still standing firm like Hadrian’s Wall. From above, it is a period preceding the castle’s f. Let’s approach this as a scientist, with measurement. From the castle side, this structure resembles the circular stump of a roofless tower, eight feet tall and twice that wide. The stones are ancient sand, compacted and weathered, stained different shades of red from iron deposited millions of years ago, but the mortar is new. But inspection is not enough—we should go in. Walk around to the other side, and an opening appears, as shown in Figure 2.1. The structure is not a closed circle, but it is a spiral wall open to the sea, and to you. Inside, a small stone bench invites you to sit. A window slit next to the bench is an eye to the outside. Surrounded by a jigsaw of rocks, you can hear the echo of waves all around and watch the blue-gray sky above. If the spiral’s opening is a mouth, then you are Jonah in the whale. You are both inside and outside at once.

Photolytic degradation of 2,4-D onZea maysleaves

Weed Science ◽  
1999 ◽  
Vol 47 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Ramarao Venkatesh ◽  
S. Kent Harrison
Keyword(s):  
Zea Mays ◽  
Time Course ◽  
Uv Light ◽  
Light Regime ◽  
Growth Chamber ◽  
Polychromatic Light ◽  
Photolytic Degradation ◽  
Microscope Slides ◽  
Glass Microscope

Growth chamber experiments were conducted to determine the effects of UV light and riboflavin on photolysis of 2,4-D applied toZea maysleaves. Droplets of 100 mg L−114C-2,4-D were applied toZ. maysleaves with and without 10 mg L−13H-riboflavin and exposed to either UV-enhanced or UV-attenuated polychromatic light in a time-course assay. Photolysis of nonabsorbed14C-2,4-D residues onZ. maysleaves was sensitized by riboflavin regardless of UV light regime, but a larger percentage of nonabsorbed herbicide was degraded under UV-enhanced light compared to UV-attenuated light. Riboflavin was almost completely photolyzed during the first 10 h of exposure; yet, photolysis of14C-2,4-D surface residues in treatments containing riboflavin increased from 59% at 10 h of exposure to 87% at 42 h of exposure. In corresponding treatments without riboflavin, photolysis of14C-2,4-D surface residues was 37% at 10 h of exposure and 84% at 42 h of exposure. In contrast, only 7% of the14C-2,4-D deposited on glass microscope slides was degraded after 42 h of exposure in the absence of riboflavin, whereas 59% was degraded in the presence of riboflavin. Photolysis of 2,4-D onZ. maysleaves in treatments without riboflavin suggests that certain epicuticular component(s) ofZ. maysacted as photosensitizers or catalytic agents that promoted photolysis of nonabsorbed 2,4-D residues.

Investigation of Hybridization Efficiency of a Sequence-Orientated Coaxial DNA Probe Microarryed on Biochips Using Atomic Force Microscope

2013 ◽  
Vol 284-287 ◽  
pp. 315-319
Author(s):  
Jui Chuang Wu ◽  
Dan Kai Yang ◽  
Yane Shu Lin ◽  
Jun Yi Chen
Keyword(s):  
Atomic Force Microscope ◽  
Fluorescent Dyes ◽  
Laser Scanner ◽  
Dna Probe ◽  
The Other ◽  
Chip Surface ◽  
Surface Probe ◽  
Atomic Force ◽  
Glass Slides ◽  
Hybridization Efficiency

Two sequence-inversed probes were microarrayed on glass slides to study the hybridization efficiency with their DNA targets. A fluorescence laser scanner and an atomic force microscope (AFM) were utilized to investigate the efficiency in different hybridization cases and their corresponding depth changes on the chips. The sequences of two targets were designed to be fully complementary to their shared DNA probe in a coaxial stacking configuration. In other words, after the first DNA target is hybridized (pre-hybridizing) onto the probe, the second one is stacked onto the non-hybridized region of the same probe. The pre-hybridizing and the second DNA targets were distinguished by two distinct fluorescent dyes. The enhancement of the hybridization efficiency was investigated through the comparison between the stacking and individual hybridization configurations. AFM was used to measure the depths of two probes at different steps of hybridization. The results indicated that the depths increased as the hybridization proceeded. Probe#1, pre-hybridizing close to the chip surface, obtained a thicker depth than the other probe pre-hybridizing away from the chip surface, Probe#2. A hypothesis was proposed to explain how the depth variation was associated with the observed hybridization efficiency.

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