w********h
发帖数: 12367 | 1 well,
(1)
when we talk about good or θ slovents, we mean we are in dilute limit.
In dilute solution with a Ns=1 (monomer solvent),
only Zimm model is applicable.
(2)
When Ns is no longer monomer solvent,
we need to use a boundary condition Ns^2< or >N(L) to define if this system is
Zimm or Rouse. Here still is dilute solution case.
That boundary condition is just to guarantee the hydrodynamics interaction
and excluded volume effect are screened out.
(3)
when Ns>Ne,
the thing is more complicated. |
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T**********e
发帖数: 29576 | 2
这个评论:
LosGangeles at 9:50 AM July 11, 2013
I think Zimm won't stand a chance if the prosecutor keeps moving the goal
post. The state wants him punished but don't know how. |
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s******e
发帖数: 1275 | 3 我觉得Dinassor也在扮演无间道角色。我知道身边的一些中国人看了类似这个帖子的辩
论之后，转变观念，认为国人应该拥枪自卫的。
Dinassor的角色有些像这次Zimm庭审中的控方，好像在故意展示自己的弱点和逻辑混乱。 |
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l****z
发帖数: 29846 | 4 Lawsuit seeks 3rd option besides male, female on US passport
DENVER (AP) — A Colorado resident denied a passport for refusing to
identify as either male or female on the application form has sued the
federal government to try to force the United States to join a handful of
other countries that allow people to get travel documents without picking a
gender.
Lambda Legal announced the lawsuit Monday on behalf of Dana Zzyym (
pronounced Zimm) of Fort Collins, Colorado, who was born with ambiguous se... 阅读全帖 |
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C*3
发帖数: 474 | 6 我们的分歧在于我认为Zimmerman有罪， 我认为不管他杀的是黑人还是白人还是其他人
种。
这个黑人在马路上走是他的基本人权，这个人权明显被Zimmerman给剥夺了。
我认为如果这个黑人非法进入别人的家里，正好被Zimmerman抓住，两人打起来，Zimme
rman开钱杀了他，那Zimmerman才是无罪。 |
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e*********u
发帖数: 3591 | 7 他走在路上，别人盘问一下他就要剥夺人权？就算是吧，那他揍gz的时候有没有
剥夺gz的人权？有罪与否不是我们认定的，是法院裁定的，我相信法院有足够的
证据相信gz是在人权快要被剥夺的情况下才开枪的，所以才会做这样的裁定。
设身处地想几个问题：
1，你会不会大半夜去别人家gated小区去转？（这不犯法，你有没有权利另说）
2，别人盘问你在什么样的情况下你会动手，打到对方头破血流？
3，如果别人揍得你头破血流，你手上有枪，你会怎么办？
Zimme |
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h*********n
发帖数: 11319 | 8 TM白死的唯一和直接原因，就是他选择把GZ往死里打。
至于成不成年，有没有枪，双方是不是住在那个小区，都是无关细节。
他在危及别人生命的同时，也放弃了法律对他自己生命的保护。
Zimme |
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s*******n
发帖数: 10426 | 9 你这个逻辑....
芝麻没有限制TM走路的权利，没有限制TM的自由，是TM攻击芝麻，芝麻还击，TM技不如
人，挂了....
Zimme |
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q*****y
发帖数: 227 | 10 可这案子的重点是Zimmerman为啥开枪把马丁打死，是因为马丁对他有潜在的致命攻击
，Zimmerman并没有剥夺马丁在路上的行走权，跟踪并不犯法，无数人已经阐明这个观
点了，难道你没仔细看案子的细节就在那臆想谁有罪谁没罪？
Zimme |
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b**j
发帖数: 20742 | 11 http://www.nfl.com/news/story/09000d5d828b6d64/article/successf
Beware the Cincinnati Bengals after this NFL draft
By Gregg Rosenthal
Around The League editor
Published: April 28, 2012 at 03:29 p.m.
Updated: April 28, 2012 at 04:03 p.m.
A lot of fans and analysts expected the Cincinnati Bengals to take a step ba
ck after their surprising 2011 campaign and subsequent playoff flameout. The
events of draft weekend should make them think again.
It's hard not to love what the Bengals ... 阅读全帖 |
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h**********r
发帖数: 2284 | 12 Has anyone still remembered George Zimmerman's case? At the early weeks the
evidence was not released and the media cried out that it's Zimmerman who
murdered Martin. However, the evidence has already shown that Zimmerman was
under attack at the time.
See photos:
http://www.wptv.com/gallery/news/news_photo_gallery/george-zimm
This might be a very bad example that no one would care about community's
interest any more, particular to those related to 类人猿.
As for the relevance to this board, what Zi... 阅读全帖 |
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l*****9
发帖数: 9501 | 13 http://www.businessweek.com/news/2012-02-27/ovarian-stem-cells-
Ovarian Stem Cells Make Human Eggs in Possible Aid to Fertility
By Ryan Flinn
Feb. 27 (Bloomberg) -- Stem cells taken from human ovaries were used to
produce early-stage eggs by scientists in Boston who may have created a new
method to help infertile women.
Females have a fixed number of eggs from birth that are depleted by the time
of menopause. The finding, published today in the journal Nature Medicine,
challenges the belief that... 阅读全帖 |
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n*****7
发帖数: 19 | 14 对polymer 自组装而言，dn/dc是分析zimm plot 的前提，可以得到聚集的Mw,除以单个
链分子量得到aggregation No.，即每个micelle有多少个链，然后结合浓度就知道单位
体积多少了micelle... |
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w********h
发帖数: 12367 | 15
何曼君老师的书里面没有详细介绍entanglement molecular weight(Me)的概念，
只是在粘度随分子量变化的图中引进了critical molecular weight(Mc)的概念，
即，eta---M^(1) when MMc.
一般而言，Mc=2-3Me.
在整个国内的高分子教学和科研中，
对于Rouse-Zimm Model和Reptation Model的介绍都太少，
当分子量低于Mc的时候，polymer melt可以用Rouse Model (Rouse)描述，
而高于Mc的时候，用Reptation Model (De Gennes, Doi, Edwards)描述。
Reptation Model得到的关于粘度在此区域的分子量依赖性为eta---M^(3),
而不是实验所得的3.4.
这种偏离目前最成功的解释是contour length fluctuations,
即分子链的末断的波动导致Reptation Model中的实际持续链长L有一修正dL.
当分子量M>>10-15Mc的时候，此因 |
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w********h
发帖数: 12367 | 16 http://www.people.virginia.edu/~blf2v/prizewin.html
Division of Polymer Physics
Prize Winners
Polymer Physics Prize
Sponsored by Ford Motor Company
(Until 2000, The High Polymer Physics Prize)
Prize Criteria
1962: Paul J. Flory 1981: Robert Simha
1963: Bruno H. Zimm 1982: Sir Samuel Edwards and
1964: Andrew Keller Pierre-Gilles deGennes
1965: Peter J.W. Debye |
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w********h
发帖数: 12367 | 17 我的意思是那两本书(尤其Doi&Edwards)不但专深，而且如果对于整个Polymer
Physics来讲的话还远远不够。Wunderlich的上下册的结晶对于高分子结晶是一份
非常经典的著作。而对于不做polymer dynamics的人来讲，de Gennes的那本小册
子已经够用来了解polymer dynamics了，而且在很多高分子物理书里都有介绍
Rouse, Zimm, Reptation theories. |
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w********h
发帖数: 12367 | 18 Even for flexible, long homo-polymers, the picture is not fully clear.
Reptation model still faces some challenging problems. For very long
chain, de Gennes predicted Stokes-Einstein behavior recovers but nobody
verified yet.
After all, Zimm, Rouse, Reptation and some boundry conditions are the
most successful approach to explain linear monodisperse polymers.
clear |
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c******h
发帖数: 4573 | 19 我怀疑millpore的油膜会吸附PNIPAM
在THF中的PNIPAM过膜老是有灰尘。TNND
动态还好说，这个静态和zimm作图怎么办啊
55555555555 |
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c******h
发帖数: 4573 | 20 我觉得离心除尘很难达到光散射的要求
尤其是做静态或者zimm作图。我的水样就是离心除尘。
在90度角测动态还行，到了小角测静态简直就是一团糟。 |
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c*******n
发帖数: 1648 | 21 It's interesting, basically you are saying DNA follow Rouse instead Zimm? I
wish I had enough time and could discuss with you intensively and learn sth
for bio guys, but I'd better to disppear in the next two weeks. Otherwise my
boss will be angry. Besides the density, diffusion coeff. will make huge
difference on your result. |
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w********h
发帖数: 12367 | 22
block copolymer根据组成比不同会有miscrophase separation。
从sphere结构cylinderical结构到lamellae结构的变化，
再细致观察，在cylindrical与layer结构之间，
有两个复杂的结构，
一个叫做Bicontinuous,
一个叫做perforated layers (HPL)结构。
其中bicontinuous结构又叫double gyro phase,
也因结构复杂被称为“水管工的噩梦”。
大分子如何运动。
通常三种理论：Zimm, Rouse, and Reptation.
在polymer chain 高于一个临界分子量Mc的时候，
粘度的分子量依赖关系由M^1变化到M^3.4.
Mc通常和一个叫做entanglement molecular weight Me的量有关系，
Mc--2~3 Me.
对于不同种类的聚合物，Me不同。
在形容M>Me的聚合物，通常用Reptation理论，
由de Gennes首先提出tube model and snake-like motion,
Doi and Edwards |
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w********h
发帖数: 12367 | 23 good discussion.
I think I need to think more..
as to my original problem,
I think my last post is already close to the "answer" (mine).
only at θ temperature can a polymer chain behaves like it is in itself.
The rest, we need to attribute to Rouse-like behavior, which means draining
effect is not negligible as in Zimm behavior in normal good or θ solvents.
In Colby and Rubinstein's new book,
they mentioned different R---M relationship.
for athermal solvent: R--M^(3/5),
Good solvent: R--M |
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c*******n
发帖数: 1648 | 24 I am more confused, because I think that θ behavior, chain conformation
and dimension are static properties. While Rouse and Zimm are dynamic
properties. How to link the θ state to Rouse behavior? What I thought θ is a
pretty much free energy thing. Does the free draining equal to
no-excluded-volume effect? Hope more input from you guys, especially on how to
link static properties and dynamic properties together.
chains.
walk
he
no
must
real
this, |
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w********h
发帖数: 12367 | 25 knot, loop are different from entanglement.
according to my diagram: if the polymer is an isolated chain in smaller
molecules,
the longer, the more like Stokes, which is basically Zimm. |
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c********r
发帖数: 15 | 26 I don't think so. SLS is used for molecular weight measurement. Remember the
zimm plot? |
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o******e
发帖数: 4 | 27 Dilute solutions have strong hydrodynamic interactions. The Zimm modelworks
well and essntially all the solvent within the pervaded volume ofthe
polymer coil moves with the coil.
The situation is very different foran unentangled polymer melt.
Hydrodynamic interactions are screened andthe Rouse model applies. The Rouse
model will only describe your data at lowfrequency (frequencies below the
reciprocal of the Kuhn monomer time TAU0). But there is always a regime at
higher frequency (motions in |
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o******e
发帖数: 4 | 28 Dilute solutions have strong hydrodynamic interactions. The Zimm modelworks
well and essntially all the solvent within the pervaded volume ofthe
polymer coil moves with the coil.
The situation is very different foran unentangled polymer melt.
Hydrodynamic interactions are screened andthe Rouse model applies. The Rouse
model will only describe your data at lowfrequency (frequencies below the
reciprocal of the Kuhn monomer time TAU0). But there is always a regime at
higher frequency (motions insid |
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c******x
发帖数: 438 | 29 Many thanks. Actually i later talked to a technician about DLS, he said DLS
is better for monodisperse particle or within very short range. For
polydispersity, he said the data may not be trusted, also dust/containmation
can casue a lot of trouble.I only want to find a short-cut, if no other
choice, may play with zimm-plot.Thanks again. |
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k*******a
发帖数: 772 | 31 说说我了解的:
DLS测量的是diffusion constant然后得到Rh (因为粒子做的是布朗运动)
SLS可以用zimm plot得到Mw, Rg, A2但是前提你要得到高分子的dn/dc也就是说溶液折
射率随高分子浓度的变化的斜率,这个比较麻烦,一般测量他的仪器不一定都有.
Rg/Rh的比值可以大概预测高分子的形状.
小角度光散射主要用在粒子比较大,微米级的时候.
直接测量persistence length的光散射方法好像没见过,不过也许有. |
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k*******a
发帖数: 772 | 32 SLS需要测量前先测量溶剂的各个角度的散射强度，也就是背景
然后测量不同浓度，不同角度的散射强度，得到的数据用zimm plot.
PS:可能还需要测量前先测量标准溶液比如Tuolune来测量Rayleigh系数 |
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D********g
发帖数: 533 | 33 可以看看高分子物理方面的书
里面有怎样Zimm Plot测量Rg，就是高分子的链段半径，和你说的这个有点像。
CNT不大清楚 没看过文章。 不过我觉得应该和测液晶高分子的Rg差不多。 应该是可行
的。
这个和显微镜的差别在于 显微镜是看的local的性质 而DLS是全局的尺度 最后的结果
是所有CNT的平均尺寸 也许更加有说服力 |
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h****J
发帖数: 56 | 34 *Amgen Will Cut 2,200 to 2,600 Jobs, Saving $1 Billion (Update2) *
By Luke Timmerman and Angela Zimm
Aug. 15 (Bloomberg) -- Amgen Inc., the world's largest biotechnology
company, will slash jobs for the first time in its 27-year history,
close plants and cut capital spending in response to declining sales of
its top-selling drug.
The job cuts will total 2,200 to 2,600, or 12 to 14 percent of the
workforce, under a plan to save more than $1 billion in 2008, Amgen said
today in a statement. Earnin |
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