Membrane Definition and 148 Threads

Hello everybody, I am chemist. and I prepare ionic membrane and placed in a home made acrylic cell containing 0.1M NaCl separated into two portions by ionic membrane. I applied DC voltage of 9.6V (using 9V battery). Using multi-meter the measured DC voltage in water was 4.45V. The distance...

Hello to all. I'm building a prototype of a portable air compressor system. I would like to place a membrane just after the tank drain that would allow the liquid water (condensate) to pass through into a canister. This membrane would allow the water to pass through by gravity. When the portable...

During a synapse, a synaptic vesicle fuses with the presynaptic membrane releasing whatever neurotransmitters it contains. Neurotransmitters are then taken in through transport proteins during re-uptake. Stimulation occurs on a regular basis for some neurons and since the neurotransmitters are...

Hi all - I'm preparing a presentation that includes circuit diagram stuff, and it's been a very long time since I've done any of that. For this circuit, http://alford.bios.uic.edu/Images/586%20images/circuit%20model (i.e. a circuit model of an isolated patch of cell membrane), I read that...

Hello, As of this moment I am trying to get in the process of writing an Extended Essay on Chladni Plates, more specifically on a circular vibrating membrane with free ends. To begin with I thought the concept could be simplified to such an extent where I could take a cross-section of the plate...

I am working on a design of a spherical dome. I tried to understand membrane theory with no success.Can anyone please help me with an clear explanation to derivation of membrane theory of shells.

Hi. Can you do a computer simulation of a membrane with a standing wave(s)/node(s) with a shape of a cube or cone? It is possible on a string so why not on a membrane. Can you do a computer simulation of a spherical membrane with a standing wave(s)/node(s) with a shape of a cube or cone...

So the equation to obtain the frequency of the modes of a square membrane is something like ω m,n = ∏ [(m/a)^2 + (n/b)^2]^(1/2) This equation can be used to get the frequency for Modes such as (2,1) and (1,2). How do I get the frequency for such modes as (2,1)+(1,2) and (2,1)-(1,2) ...

I need to know a realistic minimum biaxial tension per unit length - in N/m - for the surface of a membrane which is 27.4 mm square - with surface density 0.0912 kg/m^2 - so that it could be vertical and remain tense so that mode shapes due incoming acoustic energy would remain intact (if the...

I'm learning about a very basic model neuron, in which only potassium and chloride is permeable. Why is it that when the extracellular concentration of potassium is increased, the neuron become depolarized, whereas when extracellular concentration of chloride is reduced, the neural membrane...

I've just got a quick question that hopefully someone can answer. My question is - why does the membrane in COMSOL vibrate without you telling it to? Here are some specifics if required... In COMSOL here are my setup details: - Physics: (3D) Structural mechanics - Membrane Study...

Homework Statement I'm following a procedure in a particular paper as part of my Masters project. The paper is called 'Theoretical investigation of the sound attenuation of membrane-type acoustic metamaterials - Y Zhang, J Wen, Y Xiao, X Wen and J Wang (2012)' and can be seen...

I keep coming across the word apical and basolateral membrane in my study of plasma membranes of cells. I am wondering if the apical membrane is towards the inside of the cell (cytoplasm) or towards the outside ?

I have heard that nobody really knows how many receptors are placed on E.Coli cell membrane. Of course we know the general types of the proteins incorporated in membrane (Carrier proteins, Na+/K+-ATPase, various transporters, Ion channels) but I need to know the exact number of types and exact...

Homework Statement An inflatable membrane is filled with an ideal gas at a pressure of 0.3 bar gauge. The gas is at 40 deg C and the volume of the membrane is 100m^3. The membrane is constrained on all sides and bottom, and a force of F acts on the top of the membrane. The material the...

Hello everyone, Lets say there is a membrane, which has a channel for the solute(eg sodium) and another channel for water Now if I have a hypertonic (more sodium) solution in side A, and hypotonic (less sodium) solution in side B. Which way would water go? * I'm very confused here...

The surface of any liquid behave like a stretched membrane. Is it because of surface tension or all the possible forces acting on a liquid molecule at the surface? I asked this question because if the furface behaves stretched because of surface tension then it means that the forces making the...

Homework Statement Is it possible to find a solution to the wave equation on a circular membrane such that the shape remains constant, but rotates at a fixed rate in the angular direction? Homework Equations The Attempt at a Solution I've tried separating variables, and assuming...

Dont give me the answer that its because of surface tension. I want it in detail.

In membrane potential determination of a cell, the Goldman Hodgkin Katz equation says the contribution of an ion to diffusion potential is dependent on its membrane permeability. So in case an ion, one that has a zero permeability, is present outside the cell, using the equation , one will get...

http://www.vibsys.put.poznan.pl/journal/2010-24/noga-2.pdf Equations (9) leads to (11). How from R boundary condition do we end up with the equation in (11)?

$u_{tt} = c^2\nabla^2u$ where $\nabla^2 = \frac{1}{r}\frac{\partial }{\partial r}\left(r\frac{\partial}{\partial r}\right) + \frac{1}{r^2}\frac{\partial^2}{\partial\theta^2}$. Suppose $u(r,\theta,t) = G(r,\theta)e^{i\omega t}$. Then $$ -\omega^2Ge^{i\omega t} = c^2\nabla^2Ge^{i\omega t} $$ which...

My (probably misguided) intuition says the following : 'Take a closed loop of wire and bend it into any arbitrary shape so that it lies flat on a table. stretch a membrane over it (i.e. a soap membrane say). Then, I should be able to vibrate it at just the right frequency to generate (at least)...

Homework Statement I must find the oscillations of a circular membrane (drum-like). 1)With the boundary condition that the membrane is fixed at r=a. 2)That the membrane is free. Homework Equations The wave equation \frac{\partial ^2 u }{\partial t^2 } - c^2 \triangle u =0...

hello world long time no see..actually I've been very confused with this resting membrane potential I've sooo many questions but i'll only ask one question for now .at rest the membrane of nerve cell is permeable to potassium , potassium goes outside the cell along its concentration gradient...

Hey everybody, I'm trying to figure out what the vibration modes of a circular membrane would look like if we put some sound through it. As you may know does a circular membrane with clamped edges at radius a behave according to the wave equation. The general solution thereof has the form...

Is there any reason,resting membrane potential is cca -70mV?because teacher asked us today,and it was not enough for him to say,that it is due concentrations of ions...What is the reason of this value? Thanks

Hi guys, I am in need of a 'one-sided' membrane. Basically, something like a bad damp proofing membrane. Allow me to explain: A membrane which will allow water to pass through one-way (at a fast rate - this is where it differs from the damp proof membrane you can buy in the diy shop)...

Homework Statement I'm trying to solve the vibrations of a rectangular membrane with a rectangular hole inside. Both the inner and outer edges are fixed. I know i have to use the wave equation, but how do i write the boundary conditions in orden to incluye the hole? Any ideas? F.Y.I. I...

I have a sphere of radius 4.8mm surrounded by a membrane .2 mm that has a drug in the inner sphere and is diffusing out through the membrane. I know the saturation concentration, the partition coefficient and diffusivity of the drug. I also know that the concentration outside of the membrane is...

Hi, Was wondering if I could get some help with part b of this question? I've attached the question and my attempt in the pictures as there was a lot of data and writing, so thought this would be the easiest way. With my attempt I think I'm missing something pretty obvious, but I'm drawing...

Hi. I am currently doing an experiment regarding to the factors affecting beet root cell membrane. Some of them are pH (2,4,6,8,10) , Ethanol (1%, 25%, 50%) and Detergent(1%, 5%). I've seen that different pH, different concentration in ethanol and detergent each has different results in both...

Hi, I am solving the diffusion equation using explicit finite difference to model the diffusion of an analyte through a membrane. I am interested in the concentration of the analyte on the other side vs time elapsed. On one side of the membrane is an initial concentration, which I am...

The ribosomes have a membrane to prevent damage of the cell from the enzyme. but why are the cells not damaged when the enzymes are digesting unwanted structures, since the enzymes have to be released to digest unwanted structures.

Homework Statement Are phospholipids cholesterol?Because in one book it says that ' cholesterol molecules, like phospholipids'. I am a little bit confused. Homework Equations The Attempt at a Solution

Hello! Electric force is inversely proportional to the dielectric constant. In a textbook, this is said to be forty-fold greater for water than the phospholipid membrane. As such, ions are unlikely to cross the plasmamembrane. I assume this has something to do with preferring to stay in...

Hi, Please can anyone help me here? Consider the link below; http://online.physics.uiuc.edu/courses/phys193/Lecture_Notes/P193_Lect4_Ch4_Part2.pdf I'm just trying to qualitatively undestand the pictures in the above link. Consider Page 2 of 18 Now, consider figure 3.6...

I've just finished reading through the generally well-written Wikipedia article on membrane potential: http://en.wikipedia.org/wiki/Membrane_potential I found almost everything to be clear, but one question is nagging at me. Why do changes in membrane permeability directly affect membrane...

why simple diffusion does not require a semi-permeable membrane?

Finkelstein's "unidirectional membrane" paper The "unidirectional membrane" interpretation of black-hole event horizons originated with this paper: Finkelstein, Phys. Rev. 110, 965–967 (1958), "Past-Future Asymmetry of the Gravitational Field of a Point Particle," downloadable from his web...

Homework Statement We will deal here with a certain identified synapse in the CNS of the mooncalf (Bos lunaris). The post synaptic cell has voltage-sensitive channels like the squid axon-- a rapidly depolarizing, inactivating channel which conducts only sodium ions, and a slowly depolarizing...

I'm about to build a plate reverb and I have some thought, or questions about the plate. The set-up is as follows: A rectangular plate, firmly tensioned in the corners. A forced motion entered. 2 or more pick-ups, piezo style. I'd like to know how the plate, it would be thickness...

Hello, I am currently in the process of writing an Extended essay on the the "Effect of Tension on the fundamental Vibration of a circular Membrane" I have already completed the practical side of this by making 5 diaphragms with a 3 micron thick mylar membrane and have written up the methods...

I am interested in membrane recently.Can someone show the abc knowledge about membrane. I major in mechanics and I concern about the maths, physics and mechanics of membrane. Can somebody recommend some classic books and articles about this subject. Thanks.:smile:

Hello, I am working in the water treatment industry and for some of our tests we are using a bench scale 'high pressure' (8-10 bar) membrane filtration system. For the moment, the system comprises a tank from which water is pump into a membrane cell. A part of the flow just flows through the...

Hello, I've a book in cell biology (it's an advanced book not a crash course or something) where's written that peripheral proteins are loosely connected to the membrane. However in most sources on the internet it's written that the protein is temporally adhered to the membrane. I'm a bit...

Homework Statement Please see question attached Homework Equations The Attempt at a Solution Ok so I've been able to do the first few parts and have derived that Wm,n = c pi / L (m^2 + n^2) I've thus been able to show that the second lowest freq is a factor of root(5/2)...

Hello everyone, These are true,false questions. I'm on holiday so can't get help yet and this is not homework. 1.Increased permeability of the cell membraneto K+ than Na+ is important for maintaining resting membrane potential of cell? Ok I know this is true but I don't understand...

Hi Guys, I am new to this forum and would like to take this chance to say hello to everyone here. Basically, my question is about the mechanical translation of cell membrane lipid peroxidation. I am wondering if lipid peroxidation has any impact on the stiffness of cell membrane. If so, is...

Homework Statement I am analyzing the deflection of clamped circle polysilicon membrane with radius=1500 um and thickness=1 um. The load is constant pressure ranging from 20 uPa to 20kPa. The problem is that my analytical solution doesn't agree with the ANSYS solution. Homework Equations...