Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions

1993 ◽  
Vol 51 ◽  
pp. 876-877
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Microstructural Characterization ◽  
Building Blocks ◽  
Quantitative Information ◽  
Physical Models ◽  
Specimen Preparation ◽  
Time Resolved ◽  
Temperature Changes ◽  
Temperature And Humidity ◽  
Microstructured Fluids ◽  
Air Streams

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

scholarly journals Development of Self-Sensing Textile Strengthening System Based on High-Strength Carbon Fiber

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2062
Author(s):  
Marcin Górski ◽  
Rafał Krzywoń ◽  
Magdalena Borodeńko
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
High Efficiency ◽  
High Strength ◽  
Strain Gauges ◽  
Building Structures ◽  
Climatic Chamber ◽  
Daily Cycle ◽  
Temperature Changes ◽  
Temperature And Humidity

The monitoring of structures is one of the most difficult challenges of engineering in the 21st century. As a result of changes in conditions of use, as well as design errors, many building structures require strengthening. This article presents research on the development of an externally strengthening carbon-fiber textile with a self-sensing option, which is an idea is based on the pattern of resistive strain gauges, where thread is presented in the form of zig-zagging parallel lines. The first laboratory tests showed the system’s high efficiency in the measurement of strains, but also revealed its sensitivity to environmental conditions. This article also presents studies on the influence of temperature and humidity on the measurement, and to separate the two effects, resistance changes were tested on unloaded concrete and wooden samples. The models were then placed in a climatic chamber, and the daily cycle of temperature and humidity changes was simulated. The research results confirmed preliminary observations of resistivity growths along with temperature. This effect is more visible on concrete samples, presumably due to its greater amount of natural humidity. The strain measurement with carbon fibers is very sensitive to temperature changes, and applications of this method in practice require compensation.

scholarly journals Through-grid wicking enables high-speed cryoEM specimen preparation

2020 ◽  
Vol 76 (11) ◽  
pp. 1092-1103
Author(s):  
Yong Zi Tan ◽  
John L. Rubinstein
Keyword(s):  
Glass Fiber ◽  
High Speed ◽  
Protein Complexes ◽  
Absorption Capacity ◽  
Specimen Preparation ◽  
Water Interface ◽  
Time Resolved ◽  
Glass Fiber Filter ◽  
Liquid Absorption ◽  
Air Water Interface

Blotting times for conventional cryoEM specimen preparation complicate time-resolved studies and lead to some specimens adopting preferred orientations or denaturing at the air–water interface. Here, it is shown that solution sprayed onto one side of a holey cryoEM grid can be wicked through the grid by a glass-fiber filter held against the opposite side, often called the `back', of the grid, producing a film suitable for vitrification. This process can be completed in tens of milliseconds. Ultrasonic specimen application and through-grid wicking were combined in a high-speed specimen-preparation device that was named `Back-it-up' or BIU. The high liquid-absorption capacity of the glass fiber compared with self-wicking grids makes the method relatively insensitive to the amount of sample applied. Consequently, through-grid wicking produces large areas of ice that are suitable for cryoEM for both soluble and detergent-solubilized protein complexes. The speed of the device increases the number of views for a specimen that suffers from preferred orientations.

Laser-Induced Forward Transfer of Organic LED Building Blocks Studied by Time-Resolved Shadowgraphy

2010 ◽  
Vol 114 (12) ◽  
pp. 5617-5636 ◽  
Author(s):  
Romain Fardel ◽  
Matthias Nagel ◽  
Frank Nüesch ◽  
Thomas Lippert ◽  
Alexander Wokaun
Keyword(s):  
Building Blocks ◽  
Time Resolved ◽  
Forward Transfer

Time Resolved Measurements of Pyrolysis Products From Thermoplastic Poly-Methyl-Methacrylate (PMMA)

2009 ◽  
Author(s):  
Cory A. Kramer ◽  
Reza Loloee ◽  
Indrek S. Wichman ◽  
Ruby N. Ghosh
Keyword(s):  
Methyl Methacrylate ◽  
Exothermic Reaction ◽  
Quantitative Information ◽  
Co2 Production ◽  
Heating Chamber ◽  
Time Resolved ◽  
Poly Methyl Methacrylate ◽  
Quantitative Measurements ◽  
Ir Heating ◽  
Flaming Combustion

The goal of this research is to obtain quantitative information on chemical speciation over time during high temperature material thermal decomposition. The long term goal of the research will be to impact structural fire safety by developing a data base of characteristic “burn signatures” for combustible structural materials. In order to establish procedure and to generate data for benchmark materials, the first material tested in these preliminary tests is poly-methyl-methacrylate (PMMA). Material samples are heated in an infrared (IR) heating chamber until they undergo pyrolysis. Time resolved quantitative measurements of the exhaust species CO2, O2, HC, and CO were obtained. During heating the PMMA sample undergoes two distinct processes. First, pre-combustion pyrolysis is characterized by the appearance a peak in the THC signal between 600–650 °C. Secondly, at about 900 °C flaming combustion occurs as evidenced by an exothermic reaction reported by the thermocouples. The time sequence of the production of HC, O2 depletion and CO2 production are consistent with combustion in an excess-oxidizer environment.

The Euler number of certain primitive Calabi–Yau threefolds

2000 ◽  
Vol 128 (1) ◽  
pp. 79-86
Author(s):  
MEI-CHU CHANG ◽  
HOIL KIM
Keyword(s):  
Moduli Space ◽  
Moduli Spaces ◽  
Three Dimensional ◽  
Building Blocks ◽  
K3 Surfaces ◽  
Physical Models ◽  
Ample Divisor ◽  
K3 Surface ◽  
Superstring Theory ◽  
Two Parameters

Recently Calabi–Yau threefolds have been studied intensively by physicists and mathematicians. They are used as physical models of superstring theory [Y] and they are one of the building blocks in the classification of complex threefolds [KMM]. These are three dimensional analogues of K3 surfaces. However, there is a fundamental difference as is to be expected. For K3 surfaces, the moduli space N of K3 surfaces is irreducible of dimension 20, inside which a countable number of families Ng with g [ges ] 2 of algebraic K3 surfaces of dimension 19 lie as a dense subset. More explicitly, an element in Ng is (S, H), where S is a K3 surface and H is a primitive ample divisor on S with H2 = 2g − 2. For a generic (S, H), Pic (S) is generated by H, so that the rank of the Picard group of S is 1. A generic surface S in N is not algebraic and it has Pic (S) = 0, but dim N = h1(S, TS) = 20 [BPV]. It is quite an interesting problem whether or not the moduli space M of all Calabi–Yau threefolds is irreducible in some sense [R]. A Calabi–Yau threefold is algebraic if and only if it is Kaehler, while every non-algebraic K3 surface is still Kaehler. Inspired by the K3 case, we define Mh,d to be {(X, H)[mid ]H3 = h, c2(X) · H = d}, where H is a primitive ample divisor on a smooth Calabi–Yau threefold X. There are two parameters h, d for algebraic Calabi–Yau threefolds, while there is only one parameter g for algebraic K3 surfaces. (Note that c2(S) = 24 for every K3 surface.) We know that Ng is of dimension 19 for every g and is irreducible but we do not know the dimension of Mh,d and whether or not Mh,d is irreducible. In fact, the dimension of Mh,d = h1(X, TX), where (X, H) ∈ Mh,d. Furthermore, it is well known that χ(X) = 2 (rank of Pic (X) − h1(X, TX)), where χ(X) is the topological Euler characteristic of X. Calabi–Yau threefolds with Picard rank one are primitive [G] and play an important role in the moduli spaces of all Calabi–Yau threefolds. In this paper we give a bound on c3 of Calabi–Yau threefolds with Picard rank 1.

scholarly journals Physical models of spatial genome organization

2016 ◽  
Author(s):  
S.V. Slanina ◽  
A.V. Aleshchenko ◽  
Y.A. Eidelman ◽  
S.G. Andreev
Keyword(s):  
Cell Biology ◽  
Normal Development ◽  
Quantitative Information ◽  
Computational Method ◽  
Physical Models ◽  
Nuclear Reorganization ◽  
Hypothetical Scenario ◽  
3D Architecture ◽  
Biology Of Aging ◽  
Spatial Genome Organization

ABSTRACTRemodeling of nuclear organization occurs during normal cell development, differentiation and cancer. One of the biggest gaps of knowledge remains how to link the information on chromatin and chromosome structural organization with genes activity. In this paper we introduce some physical ideas and a general computational method demonstrating how genome 3D architecture and its remodeling can be quantitatively modeled. We study a hypothetical scenario of alterations of chromosome territories positioning in the course of cell proliferation. On this basis we obtain quantitative information about chromosomal contacts in the nucleus. We predict changes of radial distributions of contacts between chromosomal megabase domains during proliferation. The proposed modeling approach may be helpful in integrating experimental data on nuclear reorganization associated with normal development and with various diseases. This predictive modeling may find applications in genome research of normal and cancer cells, stem cell biology, biology of aging, etc.

scholarly journals Picosecond Optospintronic Tunnel Junctions for Non-volatile Photonic Memories

2021 ◽  
Author(s):  
Luding Wang ◽  
Houyi Cheng ◽  
Pingzhi Li ◽  
Yang Liu ◽  
Youri van Hees ◽  
...  
Keyword(s):  
Tunnel Junction ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junction ◽  
Data Access ◽  
Building Blocks ◽  
Spin Transfer Torque ◽  
Time Resolved ◽  
Physical Constraints ◽  
Spin Polarized ◽  
All Optical

Abstract Perpendicular magnetic tunnel junctions are one of the building blocks for spintronic memories, which allow fast nonvolatile data access, offering substantial potentials to revolutionize the mainstream computing architecture. However, conventional switching mechanisms of such devices are fundamentally hindered by spin polarized currents, either spin transfer torque or spin orbit torque with spin precession time limitation and excessive power dissipation. These physical constraints significantly stimulate the advancement of modern spintronics. Here, we report an optospintronic tunnel junction using a photonic-spintronic combination. This composite device incorporates an all-optically switchable Co/Gd bilayer coupled to a CoFeB/MgO-based perpendicular magnetic tunnel junction by the Ruderman-Kittel-Kasuya-Yosida interaction. A picosecond all-optical operation of the optospintronic tunnel junction is explicitly confirmed by time-resolved measurements. Moreover, the device shows a considerable tunnel magnetoresistance and thermal stability. This proof-of-concept device represents an essential step towards ultrafast photonic memories with THz data access, as well as ultralow power consumption.

LACUSTRINE INVESTIGATIONS IN THE GASPÉ PENINSULA

1939 ◽  
Vol 17d (10) ◽  
pp. 212-224 ◽  
Author(s):  
A. J. M. Honeyman
Keyword(s):  
Seasonal Variations ◽  
Thermal Stratification ◽  
Quantitative Information ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Oxygen Distribution ◽  
Hydrogen Ion Concentration ◽  
Temperature Variations ◽  
Temperature Changes ◽  
Lake Bottom

A study of the temperature variations in Ross Lake indicates that it is a typical "second order" lake. The seasonal variations are explicable in terms of the changes in air temperature and the resulting effects on temperature and density of the water. Thermal stratification is clearly indicated. Seasonal variations in the dissolved oxygen content of the water are largely dependent on temperature changes. The variations in acidity, alkalinity, and hydrogen ion concentration are dependent chiefly on temperature changes affecting solubility of carbon dioxide, and on the limy nature of the lake bottom. Analysis of the oxygen distribution indicates a eutrophic condition, but there is as yet insufficient quantitative information about the biological conditions to warrant definite conclusions.

A temperature-jump technique for time-resolved cryo-transmission Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 742-743
Author(s):  
H. Chestnut ◽  
D. P. Siegel ◽  
J. L. Burns ◽  
Y. Talmon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Crystalline ◽  
Temperature Jump ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Time Resolved ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Focused Beam

Transmission electron microscopy of rapidly-frozen, hydrated specimens (cryo-TEM) is a powerful way of examining labile microstructures. This technique avoids some artifacts associated with conventional preparative methods. Use of a controlled environment vitrification system (CEVS) for specimen preparation reduces the risk of unwanted sample changes due to evaporation, and permits the examination of specimens vitrified from a defined temperature. Studies of dynamic processes with time resolution on the order of seconds, in which the process was initiated by changes in sample pH, have been conducted. We now report the development of an optical method for increasing specimen temperature immediately before vitrification. Using our method, processes that are regulated by temperature can be initiated in less than 500 msec on the specimen grid. The ensuing events can then be captured by plunge-freezing within an additional 200 msec.Dimyristoylphosphatidylcholine (DMPC) liposomes, produced by extrusion, were used as test specimens. DMPC undergoes a gel/liquid crystalline transition at 24°C, inducing a change in liposome morphology from polyhedral to spherical. Five-μl aliquots of DMPC dispersions were placed on holey-carbon-filmed copper grids mounted in the CEVS environmental chamber, and maintained at 6-8°C and 80% relative humidity. Immediately before the temperature jump most of the sample was blotted away with filter paper, leaving a thin specimen film on the grid. Upon pressing the trigger, an electronic control circuit generated this timed sequence of events. First, a solenoid-activated shutter was opened to heat the specimen by exposing it for a variable time to the focused beam of a 75W Xenon arc lamp. Simultaneously, a solenoid-activated cryogen shutter in the bottom of the CEVS was opened. Next, the lamp shutter was closed after the desired heating interval. Finally, a solenoid-activated cable release was used to trigger a spring-loaded plunger in the CEVS, propelling the sample into a reservoir of liquid ethane. Vitrified samples were subsequently transferred to a Zeiss EM902 TEM, operated in zero-loss brightfield mode, for examination at −163°C.

Steep channel freezeup processes: understanding complexity with statistical and physical models

2015 ◽  
Vol 42 (9) ◽  
pp. 622-633 ◽  
Author(s):  
Mathieu Dubé ◽  
Benoit Turcotte ◽  
Brian Morse
Keyword(s):  
Degrees Of Freedom ◽  
Heat Budget ◽  
Morphological Characteristics ◽  
Large Data ◽  
Quantitative Information ◽  
Single Step ◽  
Physical Models ◽  
Data Set ◽  
Multiple Parameters ◽  
Physically Based

The development of ice dams in steep channels dictates water level variations and influences flow rates and habitat conditions. Despite the dominance of ice dam development in cold region gravel bed channels, practicing engineers and scientists have access to very little quantitative information describing this complex freezeup process. This paper aims to fill this gap by presenting a large data set on the process. The substantial variations observed in formation and melting rates from one site to the next and from one year to the next at the same site are explained with a physically-based numerical model that includes a complete heat budget applied to single step-pool sequence. The model successfully simulates the entire development of an ice dam and shows that the process depends on multiple parameters, or degrees of freedom. It also reveals that morphological characteristics greatly influence ice dam dynamics.

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