做最强的自己，与子征战兮路漫长

zhangheng1020UID: 2130513

yep, he is a very very good person... I tread him as my father.

[ 本帖最后由 zhangheng1020 于 2007-9-7 15:13 编辑 ]

zhangheng1020UID: 2130513

[ 本帖最后由 zhangheng1020 于 2007-9-7 15:12 编辑 ]

guesswhatUID: 2231211

actually, Chinese is optional, while English is compulsory.

zhangheng1020UID: 2130513

some one ask me for my photos by msn.....
so I upload this to it~~~

I knew I am bad girl....

zhangheng1020UID: 2130513

I am sensitive for the following expression:

    you are slow
    you should be faster, you are faster than this
    again,  do  it  again...
    ......


I will be very bloody when hearing those above
= =

zhangheng1020UID: 2130513

[fly]But, I am slow and weak!
So, shut up & stop complain!
Conquer it or Bear it!
heng
you are slow!
again!!
.[/fly]

[ 本帖最后由 zhangheng1020 于 2007-9-7 20:25 编辑 ]

moondy74178945UID: 2231844

:rolleyes: uhuh, u complain too, conquer and bear it~I trust u can do it~

guesswhatUID: 2231211

They call me Little Pig

zhangheng1020UID: 2130513

no, that is the photo of "mine";d:
I use that to scar other admirers


en, be good and stick on here... 43 days left (because I am not satisfied with myself yestersday )
https://bbs.gter.net/thread-734842-1-1.html

zhangheng1020UID: 2130513

Becquerel                                        From Wikipedia, the free encyclopedia                       

[size=87%]• Ten things you didn't know about Wikipedia •

                                                                        Jump to: navigation, search
                                                For other uses, see Becquerel (disambiguation).
The becquerel (symbol Bq) is the SI derived unit of radioactivity, defined as the activity of a quantity of radioactive material in which one nucleus decays per second. It is therefore equivalent to s-1. The older unit of radioactivity was the curie (Ci), defined as 3.7×1010 becquerels or 37 GBq. The becquerel is named for Henri Becquerel, who shared a Nobel Prize with Pierre and Marie Curie for their work in discovering radioactivity.
In a fixed mass of radioactive material, the number of becquerelschanges with time. Sometimes, amounts of radioactive material are givenafter adjustment for some period of time. For example, one might quotea ten-day adjusted figure, that is, the amount of radioactivity thatwill still be present after ten days. This de-emphasizes short-livedisotopes.
SIuses the becquerel rather than the second for the unit of activitymeasure to avoid dangerous mistakes: a measurement in becquerels isproportional to activity, and thus a more dangerous source of radiationgives a higher reading. A measurement in seconds is inverselyproportional. As any SI unit, Bq can be prefixed; commonly used multiples are kBq (kilobecquerel, 103 Bq), MBq (megabecquerel, 106 Bq), and GBq (gigabecquerel, 109 Bq).
When measuring radioactivity of a sample with a detector, a unit of"counts per second" (cps) is often used. Counts per second can beconverted to the absolute activity of the sample in Bq if one applies anumber of significant conversions, e.g., for the radiation background,for the detector efficiency, for the counting geometry, forself-absorption of the radiation in the sample.
The becquerel can be used for the frequency of aperiodic events; for periodic events, the Hertz, which is also defined as s–1, is used as unit.
[edit] Definition1 Bq = 1 s–1
This SI unit is named after Henri Becquerel. As for all SI units whose names are derived from the proper name of a person, the first letter of its symbol is uppercase (Bq). But when an SI unit is spelled out, it should always be written in lowercase (becquerel), unless it begins a sentence or is the name "degree Celsius".

[ 本帖最后由 zhangheng1020 于 2007-9-9 15:11 编辑 ]

zhangheng1020UID: 2130513

Gibbs-Donnan effect                                        From Wikipedia, the free encyclopedia                        (Redirected from Donnan effect)

[size=87%]• Find out more about navigating Wikipedia and finding information •

                                                                        Jump to: navigation, search
                                                
It has been suggested that this article or section be merged with Donnan equilibrium. (Discuss)
The Gibbs-Donnan effect (also known as the Donnan effect, Donnan law, or Gibbs-Donnan equilibrium) is a name for the behavior of charged particles near a semi-permeable membrane to sometimes fail to distribute evenly on either side of the membrane. [1]The usual cause is the presence of a different charged substance thatis unable to pass through the membrane and thus creates an uneven electrical charge.[2] The Gibbs-Donnan effect can prevent sick cells' sodium pumps from functioning properly. [3]
It is named after physicists Josiah Willard Gibbs and Frederick G. Donnan.


Osmotic pressure                                        From Wikipedia, the free encyclopedia                       

[size=87%]• Learn more about using Wikipedia for research •

                                                                        Jump to: navigation, search
                                               
Osmotic pressure on red blood cells


Osmotic pressure is the hydrostatic pressure produced by a solution in a space divided by a semipermeable membrane due to a differential in the concentrations of solute.
Osmotic potential is the opposite of water potential with the former meaning the degree to which a solvent (usually water) would want to stay in a liquid.
When a biological cell is in a hypotonic environment (the cell interior contains a lower concentration of water and a higher concentration of other molecules than its exterior), water flows across the cell membrane into the cell, causing it to expand due to osmotic pressure. In plant cells, the cell wall restricts the expansion, resulting in pressure on the cell wall from within called turgor pressure. The osmotic pressure π of a dilute solution can be calculated using the formula
,where
i is the van 't Hoff factorM is the molarityR is the gas constant, where R = 0.08206 L · atm · mol-1 · K-1T is the thermodynamic temperature (formerly called absolute temperature)Note the similarity of the above formula to the ideal gas law and also that osmotic pressure is not dependent on particle charge.

[ 本帖最后由 zhangheng1020 于 2007-9-9 15:17 编辑 ]

zhangheng1020UID: 2130513

MolalityMolality (m or molal) denotes the number of moles of a given substance per kilogram of solvent (not solution). Note that molality is represented by the symbol (m),while molarity is represented by the symbol (M). The two symbols arenot meant to be confused and should not be used as symbols for units.The SI unitfor molality is mol/kg. For instance: adding 1.0 moles of dissolvedparticles to 2.0 kilograms of solvent constitutes a solution with amolality of 0.5 mol/kg. Such a solution may be described as "0.5molal". The term molal solution is used as a shorthand for a"one molal solution", i.e. a solution which contains one mole of thesolute per 1000 grams of the solvent.
The determination of molality only requires a good balance, because the masses of both solvent and solute can be obtained by weighing.Using a balance is often more precise than working with volumetricflasks burettes and pipettes. Another advantage of molality is that itdoes not change with the temperature as it deals with the mass ofsolvent, rather than the volume of solution. Volume typically increaseswith increase in temperature resulting in decrease in molarity.Molality of a solution is always constant irrespective of the physicalconditions like temperature and pressure.
In a dilute aqueous solutionnear room temperature and standard atmospheric pressure, the molarityand molality will be very similar in value. This is because 1000 g ofwater roughly corresponds to a volume of 1 L at these conditions, andbecause the solution is dilute, the addition of the solute makes anegligible impact on the volume of the solution.
However, in all other conditions, this is usually not the case.
[edit] Mole fractionThe mole fraction Χ, (also called molar fraction)denotes the number of moles of solute as a proportion of the totalnumber of moles in a solution. For instance: 1 mole of solute dissolvedin 9 moles of solvent has a mole fraction of 1/10 or 0.1. Molefractions are dimensionless quantities.
This measure is used very frequently in the construction of phase diagrams. It has a number of advantages:

• the measure is not temperature dependent (such as molarity) anddoes not require knowledge of the densities of the phase(s) involved
• a mixture of known mole fraction can be prepared by weighing off the appropriate masses of the constituents
• the measure is symmetrical: in the mole fractions Χ=0.1 and Χ=0.9, the roles of 'solvent' and 'solute' are reversed.

As both mole fractions and molality are only based on the masses ofthe components it is easy to convert between these measures. This isnot true for molarity, which requires knowledge of the density.

[ 本帖最后由 zhangheng1020 于 2007-9-9 15:18 编辑 ]

zhangheng1020UID: 2130513

Osmolarity is a measure of the osmoles of solute per litre of solution, while the osmolality is a measure of the osmoles of solute per kilogram of solvent.Molarity and Osmolarity are not commonly used in osmometry because theyare temperature dependent; that is, water changes its volume withtemperature. However, if the concentration is very low, osmolarity and osmolality are considered equivalent. In calculations for these two measurements, salts are presumed to dissociate into their component ions. For example, a mole of glucose in solution is one osmole, whereas a mole of sodium chloride in solution is two osmoles (one mole of sodium and one mole of chloride). Both sodium and chloride ions affect the osmotic pressure of the solution.
The equation to determine the osmolality of a solution is given by
where

• Φ is the osmotic coefficient, which accounts for the degreeof non-ideality of the solution. In the simplest case it is the degreeof dissociation of the solute. Then, Φ is between 0 and 1 where 1indicates 100% dissociation. However, Φ can also be larger than 1 (e.g.for sucrose). For salts, electrostatic effects cause Φ to be smallerthan 1 even if 100% dissociation occurs (see Debye-Hückel equation).
• n is the number of particles into which a molecule dissociates. For example: Glucose equals 1 and NaCl equals 2.
• C is the molal concentration of the solution