scholarly journals Direct localised measurement of electrical resistivity profile in rat and embryonic chick retinas using a microprobe

2019 ◽  
Vol 1 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Harsha Kasi ◽  
Robert Meissner ◽  
Alexandre Babalian ◽  
Harald van Lintel ◽  
Arnaud Bertsch ◽  
...  
Keyword(s):  
Chick Embryo ◽  
Depth Profiling ◽  
Electrode Spacing ◽  
Retinal Tissue ◽  
Retinal Stimulation ◽  
Electrical Resistivities ◽  
Small Electrode ◽  
Measured Resistivity ◽  
First Time ◽  
Resistivity Profiling

Abstract We report an alternative technique to perform a direct and local measurement of electrical resistivities in a layered retinal tissue. Information on resistivity changes along the depth in a retina is important for modelling retinal stimulation by retinal prostheses. Existing techniques for resistivity-depth profiling have the drawbacks of a complicated experimental setup, a less localised resistivity probing and/or lower stability for measurements. We employed a flexible microprobe to measure local resistivity with bipolar impedance spectroscopy at various depths in isolated rat and chick embryo retinas for the first time. Small electrode spacing permitted high resolution measurements and the probe flexibility contributed to stable resistivity profiling. The resistivity was directly calculated based on the resistive part of the impedance measured with the Peak Resistance Frequency (PRF) methodology. The resistivity-depth profiles for both rat and chick embryo models are in accordance with previous mammalian and avian studies in literature. We demonstrate that the measured resistivity at each depth has its own PRF signature. Resistivity profiles obtained with our setup provide the basis for the construction of an electric model of the retina. This model can be used to predict variations in parameters related to retinal stimulation and especially in the design and optimisation of efficient retinal implants.

Ultrastructural studies of Chlamydia psittaci 6BC variant strains. I. Ultrastructure of the surface layers of egg-passaged 6BC strain

1973 ◽  
Vol 19 (8) ◽  
pp. 887-894
Author(s):  
Linda Poffenroth ◽  
J. W. Costerton ◽  
Nonna Kordová ◽  
John C. Wilt
Keyword(s):  
Chick Embryo ◽  
Microscopic Examination ◽  
Electron Microscopic Examination ◽  
Chlamydia Psittaci ◽  
Gram Negative Bacteria ◽  
Surface Layers ◽  
Electron Microscopic ◽  
Gram Negative ◽  
Ultrastructural Studies ◽  
First Time

Electron microscopic examination of a semipurified Chlamydia psittaci 6BC strain attenuated in chick embryo yolk sac revealed for the first time two morphologically distinct small elementary bodies which differ both in the ultrastructure of their surface layers and in their buoyant densities in sucrose gradients. Also, the morphology of the surface layers of the larger reticulate forms in cell-free systems is described for the first time. Many points of difference between the surface envelopes and internal structure of chlamydial particles and those of Gram-negative bacteria are discussed.

Non-Destructive Fluorine Depth Profiling as Quality Assurance for the Oxidation Protection of TiAl Turbine Blades

2010 ◽  
Vol 638-642 ◽  
pp. 1384-1389 ◽  
Author(s):  
Sven Neve ◽  
Kurt Stiebing ◽  
Lothar P.H. Schmidt ◽  
Hans Eberhard Zschau ◽  
Patrick J. Masset ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Ion Beam ◽  
Turbine Blades ◽  
Depth Profiling ◽  
Temperature Oxidation ◽  
Beam Analysis ◽  
Before And After ◽  
First Time ◽  
Non Destructive ◽  
Mass Increase

Using the halogen effect TiAl-alloys can be protected against high-temperature oxidation. Two different fluorination methods were applied to turbine blades. The mass increase due to oxidation can be drastically reduced compared to untreated specimen. A new vacuum chamber for ion beam analysis was developed to analyze the real parts. Using PIGE-technique the F-content as a function of depth before and after oxidation was detected. Thickness and composition of the oxide scale were measured by RBS. Both ion beam methods were non destructive and thus enabled for the first time quality assurance of the halogen treatment on real components.

scholarly journals ID: 1088 Experimental culturing of chick embryo in shell-less culture system – the first research in Vietnam

2017 ◽  
Vol 4 (S) ◽  
pp. 176
Author(s):  
Quy Xuan Nguyen ◽  
Long Thanh Dang
Keyword(s):  
Chick Embryo ◽  
Traditional Method ◽  
Culture System ◽  
Lethal Effect ◽  
Calcium Lactate ◽  
High Rate ◽  
Chick Embryos ◽  
Ideal Model ◽  
Significant Difference ◽  
First Time

Chick embryo is an ideal model with numerous applications in biomedical research. Among a variety of methods have been carried out for culturing chick embryos, shell-less culture system has a large number of advantages on accessibility, observation and manipulation. In this study, chick embryos were transferred to the shell-less culture system and the development of the chick embryos were assessed. Correlation between the diameter of sinus terminalis on the surface of yolk sac and viability of the embryos would be evaluated. In addition, calcium lactate was added to the culture system in order to find out the optimal amount. After the experiments, results showed that there was no difference between embryos in shell-less culture system and traditional method during incubation period. Secondly, the proportion of live chick embryos until embryonic day 17 reached the highest rate at 87,5% when the diameter of sinus terminalis was between 16 and 21 mm. At last, there was no significant difference between the group with 250 mg calcium lactate supplemented as compared to no supplemented group. Calcium lactate had a lethal effect on chick embryos when the supplemented content was 550 mg. In conclusion, the shell-less culture system could be able to allow the survival of chick embryos until day 21, with high rate in day 17. Besides, this has been the very first time the shell-less culture system was performed in Vietnam.

Growth of the Chick Embryo in Relation to its Food Supply

1932 ◽  
Vol 9 (1) ◽  
pp. 15-44
Author(s):  
T. C. BYERLY
Keyword(s):  
Chick Embryo ◽  
Egg Size ◽  
Initial Period ◽  
Relative Size ◽  
Yolk Sac ◽  
Physiological Processes ◽  
Order Of Magnitude ◽  
Wet Weight ◽  
Living Material ◽  
First Time

The rate of growth of the chick embryo depends upon an inherent growth rate, probably identical for all breeds. This rate is modified during incubation in direct proportion to a function of egg size. The increments in wet weight of the embryo are proportional to a function of the weight of the yolk sac, from the time of establishment of the circulation to the time of the changes preparatory to hatching. Both function and proportionality are probably identical for all breeds of chicken, regardless of egg size. The growth in weight of the allantois and the yolk sac have been measured quantitatively for the first time. The weight of the allantois in eggs of different sizes is roughly proportional to the two-thirds power of egg weight after the first three or four days of its growth. During the initial period of its development the relative size is apparently independent of breed, egg size, or embryo weight. The yolk-sac weight in eggs of different sizes is roughly proportional to the circumference of the yolk after a similar initial period of independent growth. Inclusion of the living material in the embryonic membranes in calculations of the rate of physiological processes of the embryo indicates that they are probably of the same order of magnitude throughout the incubation period rather than of sharply decreasing magnitude as supposed by some previous workers.

scholarly journals Geophysical measurements of perennial snow patches in Pirin Mountain, Bulgaria

2021 ◽  
Author(s):  
Atanas Ivanov Kisyov ◽  
Christian Veselinov Tzankov ◽  
Gergana Dimitrova Georgieva
Keyword(s):  
Ground Penetrating Radar ◽  
Subsurface Structure ◽  
High Mountains ◽  
Resistivity Tomography ◽  
Electrical Resistivities ◽  
Geophysical Investigations ◽  
The Mean ◽  
Ground Penetrating ◽  
First Time ◽  
Geophysical Measurements

Abstract. Perennial snow patches are considered as indicators of permafrost occurence. There are no large glaciers on the territory of Bulgaria but small patches of snow and firn have been observed in the high mountains in the end of the summer. Perennial snow patches are considered as indicators of permafrost occurrence. In this paper we present results from geophysical investigations of Snezhnika microglacier situated in the Golyam Kazan cirque, Pirin Mountain, Bulgaria. Ground penetrating radar (GPR) and 2D Electro Resistivity Tomography (ERT) were used to estimate the thickness of the perennial snow patch as well as its subsurface structure. Measurements started in 2018 and continued over the next three years in order to evaluate changes in the snow patches' size and thickness. The mean thickness of Snezhnika is about 4–6 m, reaching up to 8 m in some areas. ERT measurements of the deeper parts of the microglacier beds show high electrical resistivities reaching over 60000 Ωm at a depth of 4–10 m. An anomaly at this depth is likewise distinguishable on the GPR profiles. These anomalies are interpreted as frozen zones and are consistently observed on the ERT and GPR profiles in the next two years of the study. These results imply for the first time the existence of permafrost in Pirin mountain and respectively in Bulgaria.

scholarly journals Identification of increased amounts of UDP-glucuronyltransferase protein in phenobarbital-treated chick-embryo liver cells

1983 ◽  
Vol 214 (2) ◽  
pp. 517-523 ◽  
Author(s):  
B Burchell ◽  
G J Pratt ◽  
I Duffy ◽  
L West
Keyword(s):  
Tissue Culture ◽  
Chick Embryo ◽  
Microsomal Fraction ◽  
Microsomal Protein ◽  
Liver Cells ◽  
Transferase Activity ◽  
Chick Embryos ◽  
Embryo Liver ◽  
Liver Microsomal Fraction ◽  
First Time

UDP-glucuronyltransferase activity of neonatal-chick liver or phenobarbital-treated chick-embryo liver catalysed the glucuronidation of 1-naphthol, 4-nitrophenol and 2-aminophenol. Only low transferase activity towards testosterone was detected, and activity towards bilirubin was not detectable. Liver microsomal transferase activity towards the three phenols was increased approx. 20-50-fold by phenobarbital treatment of chick embryos or by transfer of liver cells into tissue culture. A single form of UDP-glucuronyltransferase, which appears to catalyse the glucuronidation of these three phenols, was purified to near homogeneity from phenobarbital-treated chick-embryo liver microsomal fraction for the first time. The use of this purified enzyme as a standard protein facilitated the identification of this protein in chick-embryo liver microsomal fraction. Further, the accumulation of this microsomal protein was observed following phenobarbital treatment of chick embryos and during tissue culture of chick-embryo liver cells. The value of this model system for the study of the induction of UDP-glucuronyltransferase by drugs and hormones is discussed.

scholarly journals Nondestructive Analysis of Wall Paintings at Ostia Antica

Heritage ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 4421-4438
Author(s):  
Bernhard Blümich ◽  
Eleonora Del Del Federico ◽  
Denis Jaschtschuk ◽  
Markus Küppers ◽  
Katelin Fallon ◽  
...  
Keyword(s):  
Depth Profiling ◽  
Integrated Approach ◽  
Wall Paintings ◽  
Egyptian Blue ◽  
Covered Wall ◽  
Ostia Antica ◽  
Roman Painting ◽  
Materials Used ◽  
First Time

Roman wall paintings at Ostia Antica were studied for the first time in situ in an integrated approach using nuclear magnetic resonance (NMR) depth profiling, portable X-ray fluorescence (XRF), and visible induced luminescence (VIL) in order to explore the materials used in their construction and gain insight into the evolution of the Roman painting technique over time. NMR revealed the signatures of covered wall paintings through details of the structure of the top painted mortar layers, and the loss of this information that can be encountered when paintings are detached from the wall for preservation purposes. XRF provided information about the pigment composition of the paintings, and VIL was used to identify Egyptian Blue. Egyptian Blue was only found in the earlier wall paintings studied dating from 1st century B.C.E. to the 1st century C.E. The pigment palette seems to become limited to iron-based pigments in the later paintings, whereas the palette of the earlier paintings appears to be more varied including mercury, lead, and copper-based pigments.

scholarly journals Large-scale ERT surveys for investigating shallow regolith properties and architecture

2018 ◽  
Author(s):  
Laurent Gourdol ◽  
Rémi Clément ◽  
Jérôme Juilleret ◽  
Laurent Pfister ◽  
Christophe Hissler
Keyword(s):  
Large Scale ◽  
Electrical Resistivity Tomography ◽  
Electrode Spacing ◽  
Resistivity Tomography ◽  
Shallow Subsurface ◽  
Subsurface Structures ◽  
Ill Posed ◽  
High Vertical Resolution ◽  
Small Electrode ◽  
Cost Efficient

Abstract. Within the Critical Zone, regolith plays a key role in the fundamental hydrological function of water collection, storage, mixing and release. Electrical Resistivity Tomography (ERT) is recognized as a remarkable tool for characterizing the geometry and properties of the regolith, overcoming limitations inherent to conventional borehole-based investigations. However, ERT measurements with a high vertical resolution remain restricted to shallow depths, essentially due to the requirement of small electrode spacing increments (ESI). Under these circumstances, the use of ERT measurements for large horizontal surveys remains cumbersome and time-consuming. Here we focus on the need to optimize the ESI parameter in order to adequately characterize the subsurface fabric. We use a set of synthetic three-layered soil–saprock/saprolite–bedrock models in combination with a field dataset. We demonstrate that oversized ESI can significantly affect our perception of shallow subsurface structures by missing important layers and increasing the ill-posed inverse problem effects. More precisely, we document how a thin surficial layer can influence inverted ERT results and cause a resistivity bias, both at the surface and at deeper horizons. To overcome this limitation, we propose adding interpolated levels of surficial apparent resistivity based on a limited number of ERT profiles with small ESI. We demonstrate that our protocol significantly improves the accuracy of ERT profiles based on large ESI. Our protocol is time and cost efficient – especially in the case of large-scale ERT surveys.

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