Cells Definition and 450 Threads

Homework Statement Please note that this is an extension of this question here: https://www.physicsforums.com/showthread.php?p=4571995#post4571995**Questions** Mirrors A and B with the space between them, including the bird, are part of the real world. Those are all a part of a basic cell...

Dose anyone know that what is the newest generation of solar cells?

Homework Statement What is the current in this circuit: http://img802.imageshack.us/img802/4646/8ekh.png Homework Equations All potential differences in a closed portion of a circuit must add to 0. Terminal Voltage = EMF - I x internal resistance. The Attempt at a Solution I do not know how...

1. About how many cells were plated to count His+ revertant colonies? How was total cell number determined? I know that the mutation freq was out of 10^7 survivors. So they had to measure the total cell number and come up with 10^7 survivors? But I'm not sure how they got this...

Proton concentration cell is made by connecting with Pt wire two acid-base solutions and measuring emf. but wire allows redox reaction, changing conc of H+ in each solution. how is original pH found- with initial emf reading?

Please tell me how to deduce reliably from galvanic cell representation, the half-cell reactions, for any cell, or vice versa. Pt(s) | H2(g) | HCl(aq) | Cl2(g) | Pt(s) Pb(s) | PbCl2(s) | HCl(aq) | H2(g) | Pt(s) Pb(s) | PbSO4(s) | K2SO4(aq) || KNO3(aq) || KCl(aq) | PbCl2(s) | Pb(s)...

I'm a high school student in AP Biology, and we are learning about how cells can absorb nutrients they need through the plasma membrane, as well as break down glucose into ATP for use. So why do cells (and organisms, for that matter) all of the sudden... Die? Why can't the cell just keep...

I don't know if this is the right forum but I'm curious. Companies are searching for alternatives like copper and zinc to make photovoltaic solar cells out of. Could aluminum ever work and be feasible, and replace current rare Earth components?

In a galvanic cell, electrons are supplied by oxidation at the anode. I am struggling to find clarity on what makes the electrons move from the anode to the cathode when a wire is connected between the two. I have come across some texts on the internet that say the electrons are attracted to the...

How does one interpret band structures (i.e. E,k solution pairs for a given Hamiltonian) for a non-primitive cell? I was looking at these slides: http://www.tcm.phy.cam.ac.uk/castep/CASTEP_talks_06/clark2.pdf Slide 9 has the "normal" silicon band structure obtained with a primitive cell...

Hi all, I would appreciate a little guidance on some circuit theory. I was wondering how a circuit behaves when there are, say two identical 10V cells, and a 1Ω bulb happily sitting in series, but then one connects another identical bulb between the two cells. Obviously the current in the first...

My (chemistry) textbook states that maximum work is never achieved in a galvanic (electrochemical) cell due to frictional heating. I've been wondering, could a cell be made with superconducting wires, cathodes, and anodes in order to achieve maximum work? Would this violate the law of entropy?

First, I am not an electrical engineer and am not to familiar with circuit boards. PROJECT: I have a static load, represented by a block. The block has three very short legs (or feet 3/8" diameter each). The feet are located concentricly under the block. Under the feet I place three thin-film...

"The size cells can grow to is limited. Of the cells shown, which one" Practice test question: 12) The size cells can grow to is limited. Of the cells shown below, which one is likely to experience the greatest difficulty as it grows larger assuming it retains the same shape? This is...

I am confused on how osmolarity of cells with water would cause a cell to swell, shrink, or burst. I know that a cell has a solution concentration of 300 mosm. In a lab that was done, we analyzed the impact of a red blood cell in solutions containing different osmolarities. For example, when a...

Test question: "Respiring cells release CO2 into the bloodstream..." 1. 2. For this question, I was thinking about the nature of CO2. It's not an acid or base, so how could it drop or raise the pH level?! So I put that the pH level won't change (B), but the real answer is C (it will...

Here is the full article, just published today: http://phys.org/news/2013-01-quadruple-helix-dna-human-cells.html The article makes it apparent that this discovery could be used to inhibit the reproduction of cancer cells. Does anyone know of any other uses that this discovery could lead to?

i'm very interested in learning about photovoltaic cells, I've read in some sites already but they all describe it in very general way, can anyone tell me on detail how does it work? thanks

Hi I need to compare solid working with \frac{1}{2}O_{2}+H_{2}O+2e^{-} \rightarrow 2OH^{-} and H_{2}+2OH^{-} \rightarrow 2H_{2}O+2e^{-} and liquid fuel cells working with H_{2}\rightarrow 2H^{+}+2e^{-} and \frac{1}{2}O_{2}+2H^{+}+2e^{-} \rightarrow H_{2}O My...

How does the efficiency of a Thin Film solar cell compare to the efficiency of a single crystal solar cell with reference to the 5 main solar cell parameters ( Iopt , Rs, Rsh, Is and n )? I know series resistance( Rs ) will probably increase in thin film cells because of grain boundaries...

Hi, I am conducting an experiment whereby I have to measure the individual performance (on a per-cell basis) of solar cells on a solar panel. The panel has 20 cells, which are 4 strings in parallel of 5 cells in series each. The entire panel has a +V and chassis GND wire that I can open or...

What problem arises or may potentially arise if drug molecules bind to plasma cells?

Thought I'd share this article w/ everyone since I found it very interesting. Imagine being able to regulate stem cells without the need for genetic manipulation or growth factors etc. Small molecules are so much easier to work with. Very interesting...

In leukaemia since immature white blood cells increase, do they overcrowd and decrease mature white blood cells. So does neutropenia and thrombocytopenia, leucocytopenia occur in leukaemia. Or does this deped on subtypes eg in some leukaemia B lymphocytes increase. Thanks :smile:

Homework Statement Within cells, small organelles containing newly synthesized proteins are transported along microtubules by tiny molecular motors called kinesins. What force does a kinesin molecule need to deliver in order to accelerate an organelle having mass 0.028 pg from rest to 2.8...

I need to calculate how much power will be generated by a solar cell at AM1.5. The cell is 1.5x3.5cm^2. I know that it is to do with the area of the cell i just don't understand how to work out the power generated without knowing things like the material. Any help would be appreciated.

If I'm "losing muscle mass", are some of my muscle cells actually disappearing? I've been running a lot lately and losing weight. Mostly getting leaner, but recently I've started to worry about losing muscle mass. I used to lift weights a lot, but I haven't done that in a few months. If I keep...

I recently started studying biology because suddenly I started getting curious about this subject. I read about the cell theory which states that all living things have cells. Is this necessary - that all living things have cells? Can't they have some different structure? Also these type of...

Congratulations, you've created a fuel cell car! Now you need electricity or fossil fuels to create hydrogen to fuel the car. So burn some coal to get electricity. How exactly does this help the environment again? What am I missing here?

Hello, PhysicsForums! I've been discussing what little I know of plate tectonics with someone and the other party has suggested that convection cells within the mantle (assuming convection really occurs at all) should eventually move such that they no longer push more matter up through...

Why does the genetic composition of sex cells of an individual vary since the genome of an individual is same throughout his/her body.

I'm doing a presentation on Hydrogen Fuel Cells for my class, but I'm having a hard time understanding how exactly it is that they work. I'm only able to find information on fuel cells and they tend to not be descriptive on the hydrogen part. If someone could please link some articles that...

So, I've read in books and on Wikipedia (see for instance http://en.wikipedia.org/wiki/Carnot%27s_theorem_%28thermodynamics%29#Applicability_to_fuel_cells_and_batteries) that the Carnot efficiency cannot be applied to a fuel cell because it is not a heat engine that produces work, operating...

Homework Statement hi I've got to do a project for college and need some direction I want to know a few things more so if you can help let me know. some of the things include (if you could answer any it would be useful): why can't we make a longer electric current to harness all the...

hi I've got to do a project for college and need some direction I want to know a few things more so if you can help let me know. some of the things include (if you could answer any it would be useful): why can't we make a longer electric current to harness all the electricity produced in a...

Homework Statement Calculate the cell potential at 25°C for the cell: Fe (s) | (Fe^2+ (0.100 M) || Pd^2+ (1.0*10^-5 M) | Pd (s) given that the standard potential for Fe^2+/Fe is -0.45 V and for Pd^2+/Pd is +0.95 V. A. +1.28 V B. +1.16 V C. +1.52 V D. +1.68 V Homework Equations E Cell...

http://www.gatech.edu/newsroom/release.html?nid=128531 Browsing the alumni stuff, I see things that make me wish I were back in school. You kids and faculty are so lucky to be able to do this kind of stuff every day. I have serious envy! Alas, wife, kids, house, bills, argh. Nothing but work...

I am an undergraduate physics student working in a biophysics laboratory, and recently on the job I have started culturing cells. We need the cells in suspension for reasons I can't disclose but the important part is that I am having some difficulties in the trypsinization process. The main...

So a human is made of cells. It is essentially a city or society of cells that live together. There is no such thing as human, it's just a bunch of cells. So human is just a natural phenomenon, an emergent property. In addition, a cell is just a bunch of atoms. I.e. a collection of atoms...

Hey, I needed a clarification regarding this. Are photovoltaic cells ohmic devices? Or if I consider an entire PV Module, will that be an ohmic device or not? I basically need to know whether I can utilize the equation P = I2*R = V*I for a cell or not.

Conditional probability & "r balls randomly distributed in n cells" Homework Statement I'm posting this in hope that someone can give me a correct interpretation of the following problem (problem V.8 of Feller's Introduction to probability theory and its applications VOL I): 8. Seven balls...

So the question is even though we may have some fair idea how multicellularity came about. How would this lead onto specialized line-aged cells in a multicellular organism ? For example differentiating to blood cells or bone cells. http://en.wikipedia.org/wiki/Multicellular_organism

There are reports that stem cells have been successfully used to cure cancer in the lungs, spleen, brain and spine. It was done on a 38 year old man from Las Vegas, but can it cure colorectal cancer? And when was the stem cell cancer therapy first successfully tested?

So we use stem cells from infants for research, but do they never take those stem cells and use it to treat people, is it not possible to make cells from other people live in your body? would your body reject and kill those cells?

Total number of cancer cells inside a tumor: 100 Each cell has a 10% chance of dying each time it divides The rate at which a cell leaves the mass is 1 every 8 hours The rate of division is 1 division / 2 hours whats the time needed to attain the 100 cells in the first place? What is the...

Please teach me this: I hear that we can make stem cells from fat tissue that is used in medical treatment.Is that correct? Thank you very much for your kind helping.

Hello! I don't understand one easy moment in high temp solid oxydes fuel cells (SOFC): 1. Oxygen ions are moving always via solid electrolite ZrO2? SOFC without load and SOFC in short circuit modes. (High temp is default mean) 2. Electrolises process need electric energy and external...

Are complex cells in the brain physically different from simple cells or is the difference in their function/role?

I did an experiment testing the thickness of a salt bridge (made of filter paper soaked in potassium nitrate) on the voltage produced from Zn and Cu half cells. This is similar to a thread someone made back in 2007. But I have no idea how to explain my findings or whether the thickness...

Hello, I was investigating 'Asymmetrical P-N Junctions'. If the doping concentration of the P and N type semiconductors are different then the P-N junction they will form will be a asymmetrically doped Junction. I searched and come up with the fact that 95% of the solar cell structures are...