Nucleophosmin And The Nucleolus
Although the nucleolus was observed in cells over 100 years ago, only recently have studies demonstrated its liquid-like properties such as fusion and flowing. The nucleolus is an MLO, best known as the center of ribosome biogenesis, though it has been associated with numerous other roles including ribonucleoprotein formation, genome stability and cancer. Nucleoli are spatially associated with nucleolar organizer regions on chromosomal DNA, and show dissociation and regrowth during different stages of the cell cycle. Internally, nucleoli are not spatially uniform and instead show more complex sub-structure.
Nucleophosmin is an abundant nucleolar protein involved in several cellular functions including ribosome biogenesis, stress response and tumor suppression. The protein consists of an N-terminal oligomerization domain , C-terminal nucleic-acid binding domain and central disordered region. It interacts with a variety of nucleolar partners including proteins and RNA, and recent studies have suggested that it helps organize the liquid phase of nucleoli.
Sub-compartmentalization in the nucleolus. Cartoon of nucleolar substructure and images of droplet within droplet structures in the nucleolus. Figure adapted with permission from Feric et al. Cell 165:1686.
States: Gas Liquid And Solid
Gas, liquid, and solid are known as the three states of matter or material, but each of solid and liquid states may exist in one or more forms. Thus, another term is required to describe the various forms, and the term phase is used. Each distinct form is called a phase however, the concept of phase defined as a homogeneous portion of a system extends beyond a single material, because a phase may also involve several materials. For example, a homogeneous solution of any number of substances is a one-phase system. Phase is a concept used to explain many physical and chemical changes .
The Special Case Of Water
A special case that is commonly discussed is the phase diagram of water. In the diagram from above, the dotted green line represents the solid-liquid coexistence curve in the phase diagram of water.
We can see that for the average substance, raising the pressure of the liquid will cause it to cross the curve and become a solid. However, for water, raising the pressure of the solid may cause it to cross the curve and become a liquid. This behavior is a consequence of the low density of the crystal structure of ice, which contains a large amount of free space due to hydrogen bonding.
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Pyrenoids And The Magic Number Effect
Pyrenoids were first identified over 200 years ago, but details of their internal structure are still emerging. An adaptation of certain eukaryotic algae, pyrenoids concentrate the enzyme Rubisco and its substrate CO2 to improve the specificity of the first step of photosynthesis. While initial conflicting evidence from electron micrographs favored various solid-assembly organizations, recent studies have instead suggested a dynamic and liquid-like pyrenoid model.
Essential Pyrenoid Component 1 is required for Rubisco localization to the pyrenoid and is proposed to link Rubisco holoenzymes to form the pyrenoid matrix. EPYC1 is highly disordered and likely forms weak interactions with Rubisco. Though both components were found to diffuse within the pyrenoid, they did so at different rates, suggesting that the diffusing unit is not a stable EPYC1-Rubisco complex.
Cartoon of the magic number effect. When the number of valences on one of the components is a multiple of those on the other , a small oligomer satisfies all valences and reduces phase separation. When this condition is not satisfied, larger networks of interacting species are formed leading to LLPS.
Phase Definition And Examples
- Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
- B.A., Physics and Mathematics, Hastings College
A phase of matter is characterized by having relatively uniform chemical and physical properties. Phases are different from states of matter.
The states of matter are phases, but matter can exist in different phases yet remain in the same state of matter. For example, liquid mixtures can exist in multiple phases, such as an oil phase and an aqueous phase.
The term phase may also be used to describe equilibrium states on a phase diagram. When phase is used in this context, it’s typically synonymous with a state of matter because the qualities that describe the phase include the organization of matter as well as variables such as temperature and pressure.
Example Question #: Help With Melting And Freezing
The following is the phase diagram for .
High temperature and low pressure
Low temperature and high pressure
High temperature and high pressure
Low temperature and low pressure
High temperature and low pressure
Sublimation refers to the phase change whereby a substance goes directly from solid to gas. At high temperature and pressure water will be more likely to melt and than evaporate. At low temperature and low pressure, the water will likely stay solid. Likewise at low temperature and high pressure. At high temperature and low pressure, the ice will be most likely to sublimate. This is clear if one looks at the phase diagram for water. High pressure makes it energetically favorable for water to melt before evaporating. Keeping the pressure low, however, makes it more favorable to pass straight into the gaseous phase.
There are six phase changes possible. Transition from solid to gas is sublimation, while transition from gas to solid is deposition. Transition from solid to liquid is melting, while transition from liquid to solid is fusion . Transition from gas to liquid is condensation, while transition from liquid to gas is vaporization . Each phase transition is considered a physical change, not a chemical change, because the identity of the compound remains unchanged.
This is a scientific error that has been created in the heating curve
These are times in the experiment when the scientists stopped heating the substance
What Are Phase Chase Diagrams
A phase transition occurs when a substance changes from one state of matter to another state. There are three primary states of matter: liquid, solid, and gas.
A phase diagram is a plot that illustrates the different phases of a substance across multiple variables, most often temperature and pressure. The diagram can help to demonstrate how changing these variables affects the state of matter of a particular substance.
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Phase Change In Daily Lives
We know how it feels to finally get your hands on the ice cream which you made it all by yourself and put it in the freezer, so it turns into ice. This is one of the ways you are, indeed performing a phase change experiment. The phase change is happening all around us, from water being evaporated to form clouds to cloud showering rain. Everything we see around us is in the phase change or has completed its phase change. In addition to this, the phase change is one of the basic concepts of chemistry, but it works as the foundation of other complex concepts which you will study in higher classes.
Phases Out Of Equilibrium
While phases of matter are traditionally defined for systems in thermal equilibrium, work on quantum many-body localized systems has provided a framework for defining phases out of equilibrium. MBL phases never reach thermal equilibrium, and can allow for new forms of order disallowed in equilibrium via a phenomenon known as localization protected quantum order. The transitions between different MBL phases and between MBL and thermalizing phases are novel dynamical phase transitions whose properties are active areas of research.
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Applications In Tissue Engineering
TIPS is a relatively simplistic approach to fabricating nanofibrous scaffolds resembling the fibrillar nature of collagen within the natural ECM. Scaffolds produced using phase separation have three levels of hierarchical architecture: macro- and microporosities which are determined by the addition of porogens, interfiber distance/scaffold density which is determined by polymer concentration, and fiber diameter which is determined by the temperature, the solvents used, and the processing variables . Such multidimensionality enables tissue engineering platforms to be tailormade to cater for different tissue types. For example, Ma and colleagues used the TIPS technique to synthesize a range of small-diameter vascular grafts from PLLA . The structural features were adjusted to resemble the nanofibrous ECM by varying the solvent ratio, phase separation temperature as well as the polymer concentration. Similarly, Lee et al. used TIPS to fabricate porous and highly interconnected PLLA scaffolds for cartilage regeneration . Here, scaffold porosity and interconnectivity were controllable by adjusting the size of the integrated NaCl particles which served as porogens. Ahmadi et al. developed PLGA microcarriers using TIPS technique to promote adhesion, growth, and subsequent release of smooth muscle cells which could be beneficial in the treatment of conditions associated with muscle damage and atrophy .
E.J. Tocce, … C.J. Murphy, in, 2011
Key Concepts And Summary
The temperature and pressure conditions at which a substance exists in solid, liquid, and gaseous states are summarized in a phase diagram for that substance. Phase diagrams are combined plots of three pressure-temperature equilibrium curves: solid-liquid, liquid-gas, and solid-gas. These curves represent the relationships between phase-transition temperatures and pressures. The point of intersection of all three curves represents the substances triple pointthe temperature and pressure at which all three phases are in equilibrium. At pressures below the triple point, a substance cannot exist in the liquid state, regardless of its temperature. The terminus of the liquid-gas curve represents the substances critical point, the pressure and temperature above which a liquid phase cannot exist.
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Thermally Induced Phase Separation
The TIPS method can produce homogeneous and highly porous scaffolds with highly anisotropic tubular morphology and extensive pore interconnectivity . This technique allows controlling the macro- and microstructures of the scaffolds. The morphology of the porous membrane varies depending on the polymer, solvent, concentration of the polymer solution and phase separation temperature. Pore morphology, in turn, affects the mechanical properties of the scaffold. The controlled phase separation of the polymer solution can be induced in several ways, including non-solvent-induced phase separation, chemically induced phase separation and thermally induced phase separation. The membranes obtained from this process usually exhibit oriented tubular pores of diameters of several hundred micrometres and an isotropic pore network of smaller pore size connecting the large tubular pores, as Fig. 4.3 shows . Foams are prepared by rapidly cooling the polymer solution to a lower temperature, in order to solidify the solvent and induce solidliquid phase separation. The samples are then freeze dried for a longer duration to ensure complete removal of solvent.
4.3. SEM micrographs showing the microstructure of PDLLA/Bioglass®-filled composite foams : orthogonal to the pore direction and parallel to the pore direction .
Sample Fractionation With Stacked Sorbents
Figure 2. Scheme of fractionation using stacked columns. Assembled stack of seven capture columns filled with different sorbents. Disassembled construct ready for elution of the captured proteins. SDS-PAGE analysis of the seven eluates from single disassembled columns . Adsorption buffer was Tris-phosphate elution was operated by means of either a mixture of trifluoroacetic acidwateracetonitrileisopropanol or of ammoniawateracetonitrileisopropanol. The position of IgG and of HSA is highlighted. IgGs appear as a single band at Mr155 kDa since disulfide bonds have not been reduced. Prefractionation techniques in proteome analysis: the mining tools of the third millennium, Electrophoresis 26: 297319.)
C.R. Wilson, in, 2010
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Phase Separation During Polymerization
Phase separation or domain formation is an important feature in many reactive systems such as segmented polyurethanes and ureas, rubber-modified epoxies and low-shrink unsaturated polyester resins. It not only controls property development in reactive processing, but is also highly coupled with the reaction kinetics and rheological changes. For thermoplastic blends and solutions, temperature jump is a common way to initiate and to control the phase separation . For reactive systems, phase separation may be affected by not only the temperature changes but also the change of phase boundary due to polymerization and the change of reactant compositions due to unequal resin reactivity .
Figure 9. Phase separation due to temperature jump and polymerization
Because of its complexity, polymerization-induced phase separation has not been well understood. The onset of phase separation can be predicted using the Flory-Huggins relation.153 For a mixture of two polymers A and B
where NA and NB are the number of repeat units on the A and B chains, is a measure of the interaction between chains A and B and can be estimated from their solubility parameters,
where i is the volume fraction of component i, and Q = V2/V1 The parameters V1, Q and vary during polymerization as
S K MISRA, A R BOCCACCINI, in, 2007
State Symbols And Phase Changes
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- The difference between chemical and physical changes as it affects chemical reactions.
- The different phases of matter, the state symbols and the different terms for them.
- The terms used to describe phase changes.
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An Introduction To Phase
Whenever we discuss thermodynamics within the realms of Chemistry, the prospect of phase plays a significant role. In essence, the idea of a phase of a matter can be understood via the changes in their state that occur with differences in their surrounding temperatures and other conditions. However, such differences in the state of matter do not alter the chemical composition of the matter. To put it simply, the phase state of matter is a homogenous quantity, meaning it is constant in its chemical composition.
Phase Separation Of Shape Memory Polyurethanes
Phase separation is one of the most important criteria for classifying whether a polyurethane will have SMEs. Extensive research studies on the parameters that affect phase separation have been conducted . The soft-segment content has been proven as one of the major parameters which affect the phase separation process. When the soft-segment content is too low, the soft segment will be embedded into the hard segment domain and vice-versa. Typically, 30 to 70% of the soft segment content will be taken at phase separation.
Li and Cooper examined PTMO-based PUs through the use of a high-voltage electron microscopy to reduce electron damage. Their experiments showed that no significant phase separation exists when the HSC is 26 wt.%. Some short cylinders are found when HSC increases to 33 wt.%. Furthermore, lamellar morphology exists when HSC increases to 50 wt.%, which indicates a complete process of phase separation. The PU sample with 50 wt.% HSC was then annealed at 125 °C for 24 hours. The HVEM micrograph showed longer lamellae with uncharged inter-lamellae spaces, which indicates a more complete phase separation process due to the rearrangement of segregation below the hard-segment Tm.
L. James Lee, in, 1989
Three Examples: Proteins Mlos And Function
Here, we discuss three protein/MLO systems with important cellular functions. Our main goal is to highlight physical chemistry principles and their influence on MLO properties and function. We discuss how interactions discussed above direct LLPS for Ddx4 and nucleophosmin, how functional sub-compartmentalization in the nucleolus can be explained by simple physics, and how magic numbers and valency matching may influence LLPS in the case of the pyrenoid.
Chemistry: Phase Equilibrium Phase Rule & Degrees Of Freedom Notes
Phase equilibrium is the study of the equilibrium which exists between or within different states of matter namely solid, liquid and gas.
- Equilibrium is defined as a stage when the chemical potential of any component present in the system stays steady with time.
- Phase is a region where the intermolecular interaction is spatially uniform or in other words physical and chemical properties of the system are the same throughout the region.
- Within the same state, a component can exist in two different phases such as allotropes of an element.
- Also, two immiscible compounds in the same liquid state can coexist in two phases.
Applications of Phase Equilibrium
- Phase equilibrium has a wide range of applications in industries including the production of different allotropes of carbon, lowering of the freezing point of water by dissolving salt , purification of components by distillation, usage of emulsions in food production, pharmaceutical industry, etc.
- Solid-solid phase equilibrium has a special place in metallurgy and is used to make alloys of different physical and chemical properties.
- For instance, melting point of alloys of copper and silver is lower than the melting point of either copper or silver.
Phase Diagram of CO2
Terms used in Phase Rule
Before studying the phase rule, it is necessary to explain the meaning of phase, component, and degree of freedom.
Component & Number of Components