l**n
发帖数: 109 | 1 native gel 确实是没有办法时的选项。
ion exchange可以先算一个理论的PI，定好buffer的pH，再做一个很缓的梯度洗脱。你
不需要知道哪个是哪个，反正要收集fractions。
其实有个问题是，就算楼主分离了monomer，也有可能再次聚集。需要screen buffer，
找到可以稳定monomer的条件 |
|
a****k
发帖数: 1130 | 2 就是说，你拿自己的sample run一个gel filtration column，collect每一个faction，然后用这些fraction做western blot （注：这时候SDS-PAGE会让蛋白变性根本就不重要，你只是要确定自己的蛋白是在哪些fraction里面）。gel filtration的每个fraction根据和standard蛋白位置的比较，是可以知道大概的size的，那不就知道你的protein的size了吗。你已知monomer是550Kda，到时候不就知道是monomer还是tetramer了吗
gel |
|
D***a
发帖数: 516 | 3 从一篇文章上抄来的：
cDNA encoding 'artificial' SUMO-2 'polymers' was generated by ligating PCR
products encoding DeltaN11–SUMO-2 while simultaneously digesting with
restriction enzymes specific for BamHI (N-terminal site) and BglII (C-
terminal site) in T4 DNA ligase buffer, 150 mM NaCl, 0.1 mg ml- 1 BSA at 22
°C for 5 h (enzymes and buffers from New England Biolabs). This created a
range of cDNAs encoding DeltaN11–SUMO-2 cDNA 'monomers' and 'multimers'
that were separated by agarose gel electrophoresis ... 阅读全帖 |
|
r******0
发帖数: 2753 | 4 这么粗浅的问题还想难倒我们？切！
这个高分子应该是一个copolymer，结构比较复杂，我们测量了它在各种溶剂中的溶解度，发现都不太好（换了好几种溶剂都没把瓶子洗干净），估计有一定程度的交联，所以表征比较困难。最后我们把工作的重点转移到monomers的官能团活性上，希望能从这方面的研究来推测和验证形成的高分子的结构，我们做了......（哈，回到小分子反应了吧）。我们还发现另一个结构相似的monomer也能生成类似的copolymer......（NND，又做砸了一锅）。
刚才忘了说性质，我们认为这种高分子在粘接剂应用上会有很大的潜力，它不但在极性表面上有很好的粘性（粘在玻璃瓶上洗不下来），而且对非极性表面如塑料（洗瓶子的时候，试管刷上也粘了不少），金属表面如不锈钢（小药铲上也粘了不少）都表现了很好的粘性。对于它能在各种不同的表面都产生很好的粘着性的机理，我们还在进一步的研究中。 |
|
j*****n
发帖数: 26 | 5 哇塞！！！！！！！！！！！！！！！
膜拜啊～～神啊～～～
比起罗斯同学
偶的书都算是白读了
解度，发现都不太好（换了好几种溶剂都没把瓶子洗干净），估计有一定程度的交联，
所以表征比较困难。最后我们把工作的重点转移到monomers的官能团活性上，希望能从
这方面的研究来推测和验证形成的高分子的结构，我们做了......（哈，回到小分子反
应了吧）。我们还发现另一个结构相似的monomer也能生成类似的copolymer......（
NND，又做砸了一锅）。
性表面上有很好的粘性（粘在玻璃瓶上洗不下来），而且对非极性表面如塑料（洗瓶子
的时候，试管刷上也粘了不少），金属表面如不锈钢（小药铲上也粘了不少）都表现了
很好的粘性。对于它能在各种不同的表面都产生很好的粘着性的机理，我们还在进一步
的研究中。 |
|
d*****i
发帖数: 77 | 6 【 以下文字转载自 Macromolecules 讨论区 】
发信人: dejinli (waiting for rocket), 信区: Macromolecules
标 题: 能用RAFT 合成纯block copolymer吗？Macro chain transfer agent 加AIBN和monomer
发信站: BBS 未名空间站 (Tue Jul 12 23:07:51 2011, 美东)
带thio的Macro chain transfer agent （如P4VP-CTA)加AIBN和monomer（如styrene）
能用RAFT合成纯P4VP-co-PS 的block copolymer吗？没做过RAFT。不过从机理来看理论
上应该会有一半是PS 的homopolymer啊！
不知我是否理解有误。请大侠指教！
拜谢！ |
|
d*****3
发帖数: 65 | 7 杂志：Designed Monomers and Polymers，2011, 14(4), 367-381
网页：http://brill.publisher.ingentaconnect.com/content/vsp/dmp/2011/00000014/00000004/art00006
作者：Yi, Shixu; Men, Jian; Wu, Difeng; Yang, Meijia; Sun, Huiqin; Chen, Hua
; Gao, Guowei.
题目：Synthesis, characterization and properties of 1,4-bis(naphthalen-1-
ylethynyl)benzene and its derivatives: monomers of oligomers or polymers
based on linear 1,4-phenylethynyl or 1,5-naphthylethynyl subunits.
Many thanks! |
|
S***k
发帖数: 158 | 8 这问题我自己在网上查了好长时间了，自己也做过一些尝试性的实验，但是结果都不是
很好。所以想在这里请教一下大家，希望有经验的前辈不令赐教。
我现在的目标是合成acrylic acid和acrylamide的copolymer，目标是合成（PAA-co-
PAM）random copolymer而不是block copolymer。聚合的手段是自由基聚合（living
radical polymerization：RAFT）。
我查到的文献和wiki都说，如果直接在一开始就把两种monomer放到一个烧瓶，同时开
始反应，那么产物很有可能是block copolymer。可是我的monomer的propagation
constant差别在一个数量级以内，那么如果一开始就放在一起的话，是不是也会倾向于
生成block copolymer呢？
如果这样做确实会导致生成block copolymer的话，那么我应该怎么做才能生成random
copolymer呢？
另外，检测copolymer是block还是random的方法，除了测Tg，做C-NMR以外，还有什么
比较有效的方法么？
在这里... 阅读全帖 |
|
e****d
发帖数: 16 | 9 I have synthesized a biphenol monomer which is said to be useful in
preparation of polyesters.I am not sure whether it can be used in solution
polycondensation.
In the bulky structure of the monomer, there are two groups(4-hydroxyphenyl-).
what are the common methods when polyesters are prepared?? |
|
y****u
发帖数: 50 | 10 As he said:
"Choosing comonomers that have reactivity ratios close to 1 produces
statiscitical copolymers, where the radical chain ends react as often with
their own monomer as they do with the others, assuming equal concentrations of
both monomers. If both the reactivity ratios are significantly higher than 1,
indicating that the racdical would prefer to homopropagate rather than
cross-propagate, the backbone copolymer exhibits a more blocky structure. If
both are much lower than 1, indicating |
|
w******r
发帖数: 43 | 11 We distilled styrene monomer like following.
1. Add CaH2 into styrene monomer,then, use liquid N2 ti frozen it and degass
it under high vacuum.
2. Stir it for 24 hours.
3. Distill it under vacuum at the temperature of 60~80 C, depending on your
vacuum. We used frozen-distilling technique. Pull high vacuum on two fask and
system. Imerse the empty flask into liquid N2. Close the vaccum line and open
the valve of the other flask which has styrene inside. You also need to heat
styrene containing fla |
|
c****n
发帖数: 134 | 12 The boss just told me that I can't finish before my graduation.
In addition, this group doesn't have much experience with photoelectrical
properties.
copolymerization can be difficult when there is vast difference in the nature
of the two monomers.
vinyl carbazole is the most reactive monomer in cationic polymerization. |
|
c****n
发帖数: 134 | 13 This criterion was listed in Quirk's book "Anionic polymerization",
but personally I don't think it is a good criterion.
Block copolymer may not be formed if you add propylene to living anionic
polystyrene...
block copolymer will be formed only when two monomer are similar in reactivity
in a specific polymerization (such as styrene and butadiene in anionic
polymerization). when the two monomers are quite different in reactivity, the
block copolymer may not be formed or there may be contaminatio |
|
b*****h
发帖数: 29 | 14 I want to fill the monomer solution inside some 100-200 nm hoses, then
crosslink it. So I can get some fibres.
F rubber is hard to synthesis?
also concened with composites, is that easy to fill magnetic particles inside
the hoses?
there are sitll some questions about the despertion of these particles in
monomers.
I need fabricate some magnetic fibres to simulate human cilia.
any briliant idea? |
|
b*o
发帖数: 47 | 15 A lot of good points. I was thinking to re-construct a unified physics
framework for these heterogeenous macromolecules, i.e., not starting from
flexible homegeneous chains and add more features, but start from the basics:
strong monomer-monomer interactions and chain conectivity, a physics framework
really unifying the conformation entropy and enthalpy. Welcome comments.
在 cashine (Who Am I) 的大作中提到: 】
distinguished
complexity
different
than
elements
though |
|
b*o
发帖数: 47 | 16 I am very interested in this and looking forward to your publication. In
Edwards' derivation, I think the attraction part has the physical origin of
the monomer space packing entropy de Gennes mentioned. The polymer chain in
melt (supposedly polymer good solvent, i.e., kai=0) and in theta solvent both
shrink from that in good monomer solvent, but with different physical driving
force: entropy in the melt case while enthalpy in the theta solvent case, I
think.
off.
=
correlation
of
interaction
i |
|
b*o
发帖数: 47 | 17
a
An interesting idea, but polymer chain in vacuum should actually act as in
very bad solvent - strong monomer-monomer attraction due to van der Waals
forces and no solvent translational entropy to swell it - resulting in a
collapsed globule - R~N^(1/3). |
|
w********h
发帖数: 12367 | 18 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. |
|
w***o
发帖数: 3830 | 19 ft... Cp2ZrCl2 is not too bad, but i still recommend you be extra careful.
you mix metal and MAO to form the real active metal center, then add monomer
to polymerize. If you add metal, monomer, nothing happened, then u add MAO,
active center starts to form and your PDI suffers. |
|
s*****o
发帖数: 65 | 20 Thank you so much for your reply. It is very helpful.
They told me they have two batches of cyanoacrylate monomer. Chemically they
are same. The react and polymerized differently. They think this is because
the end group difference. The did GC and find no difference. So they like an
intern go there to do some GPC and tell the end group difference. It looks
they have a GPC.
They will make discision on this position today or Monday. So can I email them
and say: I can use GPC fractionate each monom |
|
s****e
发帖数: 2934 | 21 不过我真的不知道怎么来严格定义。sol－gel的概念大家都知道，让我从这里说起。
sol－gel在书中的定义是，多官能团的monomer在crosslink的过程中会产生凝胶现象。就
是结成不能流动的一块胶状物。在这个不能流动的网络中，还有一部分的高分子是可溶的
，流动的，叫sol，不流动的叫gel，随着时间的延长，能流动的部分仍然可以反应，从而
成为gel的一部分。
好，我的问题是，所有的多官能团的monomer在crosslink的过程中都会产生凝胶现象吗？
比如凝胶现象的产生是否要在特定的温度，特定的单体浓度，还有特定的反应速度？比如
，如果浓度很低，那么反应的速度也很慢，这个体系能最终达到凝胶点吗？
如果我有A，B两种star polymer，arm的末端分别有functional group a和b，a和b会发生
反应生成化学键。那么这样两种polymer一旦混合，是不是会发生crosslink生成A，B有序
排列的network呢？
再进一步说，如果我有A，B两种粒子，对不起，我实在不能精确定义这种情况，只能比方
我的这两种粒子的表面都长了高分子的毛毛，毛毛的末端有可以发生 |
|
r******0
发帖数: 2753 | 22 Your boss could be wrong. I don't think solvent has much effect on the
decomposition temperature of initiators, but it does affect a lot on the
propagation step. High temperature initiators, like t-butyl peroxide,
usually used to polymerize sluggish monomers. On the contrary, low
temperature initiators used to polymerize sensitive monomers. |
|
y***e
发帖数: 6082 | 23 monomer A and monomer B 参与共聚的活性和空间位阻差别挺大的，solution-based
polymerization已经证明两者能共聚，现在引入到surface体系作surface grafting，
反应完了用什么方法或表征手段证明那个惰性单体参与了共聚呢？IR可以看官能团，但
很难说明惰性单体是chemical bonding上去的，还是non-specific adsorption给吸在
表面的呢？还有些具体情况，俺在回帖讨论中慢慢说明 |
|
p**********m
发帖数: 472 | 24 我只想表征， 并没有想到如何去合成。
这个copolymer我其本不知道monomers都是哪些，而且这些monomer都是根据几率在加热
的情况下自组装成一个个不同的copolymer，
应该用什么方法去表征这些东东呢？
或者推荐一本书专门讲如何表征copolymer， 知道他们的结构信息。 |
|
t***u
发帖数: 20182 | 25 1.need to remove the inhibitor
2.how pure is your monomer
3.toluene-chain transfer agent
4.AIBN at 80 oC has a half life of about 10min?
5.concentration too low
6.monomer to initiator ratio,like 10 to 1? |
|
r******0
发帖数: 2753 | 26 I guess the key problem is the concentration. And THF is a typical solvent
when AIBN is used as initiator. If your monomer and polymer can be dissolved
in THF, I would suggest that. For 0.3g of monomers, 1g THF should be good
enough. Anyway, good luck. |
|
m*****e
发帖数: 1506 | 27 The easy way is to polymerize F-containing vinyl monomers from an OH-
functionalized initiator by ATRP, or from an OH-containing transfer agent by
RAFT.
Anionic polymerization followed by end capping with epoxide is the most
efficient way.
ROP of cyclic ester is also a common way to introduce OH- chain end, but you
need to synthesize F-containing monomer |
|
S***k
发帖数: 158 | 28 这问题我自己在网上查了好长时间了，自己也做过一些尝试性的实验，但是结果都不是
很好。所以想在这里请教一下大家，希望有经验的前辈不令赐教。
我现在的目标是合成acrylic acid和acrylamide的copolymer，目标是合成（PAA-co-
PAM）random copolymer而不是block copolymer。聚合的手段是自由基聚合（living
radical polymerization：RAFT）。
我查到的文献和wiki都说，如果直接在一开始就把两种monomer放到一个烧瓶，同时开
始反应，那么产物很有可能是block copolymer。可是我的monomer的propagation
constant差别在一个数量级以内，那么如果一开始就放在一起的话，是不是也会倾向于
生成block copolymer呢？
如果这样做确实会导致生成block copolymer的话，那么我应该怎么做才能生成random
copolymer呢？
另外，检测copolymer是block还是random的方法，除了测Tg，做C-NMR以外，还有什么
比较有效的方法么？
在这里... 阅读全帖 |
|
s*****n
发帖数: 741 | 29 I recently coated a PTFE (poly tetra fluoro ethylene) device with some
methacrylat. The coating layer gave round disk like uncontinued morphology
on the device surface, we need get even surface.
I used simple coat method, dip the device into the mehacrylate monomer/
initiator solution, take it out and let the monomer polymerize on the device
surface.
Any suggestions? Thanks in advance, do you think spin coating would help? or
any other coating method? |
|
l*********p
发帖数: 197 | 30 在acrylate polymer的表面通过michael addition反应上一层amine,
如何知道amine的数目???
别人说可以用XPS来测,但不是很清楚怎么测
还有,有没有其他的办法啊?
polymer是用acrylate的monomer crosslink出来的,
是不是也没法通过monomer的量来计算啊?
谢谢了. |
|
x********i
发帖数: 905 | 31 Intel STS 2015 Finalists
Anandapadmanaban, Eswar
Dr. Ronald E. McNair Academic High School, Jersey City, NJ
The ThereNIM: A Touch-less Respiratory Monitor
Ashkin, Emily Lorin
Providence Day School, Charlotte, NC
A Novel Synergistic Approach for Enhancing Immunotherapy in the Treatment of
Melanoma
Chemparathy, Augustine George
Dougherty Valley High School, San Ramon, CA
Accumulation of the Biodiesel Precursor Triacylglycerol Offsets Oxidative
Stress in the Model Alga Chlamydomonas reinhardtii
Cui... 阅读全帖 |
|
发帖数: 1 | 32 07 Nov 2019
Just as the clamor about Biogen’s seeking FDA approval for aducanumab with
one positive Phase 3 trial started to die down, a Chinese company garnered a
regulatory thumbs-up for its drug, also with one Phase 3 trial. On November
2, Shanghai Green Valley Pharmaceuticals announced that China’s National
Medical Product Administration (NMPA) had conditionally approved GV-971, aka
oligomannate, for the treatment of mild to moderate Alzheimer’s disease.
Full approval, expected to come in sp... 阅读全帖 |
|
e*c
发帖数: 395 | 33 海水变油，成本3到6刀一加仑。预计8到10年后可以海试。这个成了以后是不是驱逐舰
也能靠航母加油了？
http://www.nrl.navy.mil/media/news-releases/2012/fueling-the-fl
Fueling the Fleet, Navy Looks to the Seas
09/24/2012 07:00 EDT - 117-12r
Contact: Daniel Parry, (202) 767-2541
Refueling U.S. Navy vessels, at sea and underway, is a costly endeavor in
terms of logistics, time, fiscal constraints and threats to national
security and sailors at sea.
In Fiscal Year 2011, the U.S. Navy Military Sea Lift Command, the primary
supplier of fuel and oil to ... 阅读全帖 |
|
s******r
发帖数: 7 | 34 Wanhua Chemical Recruiting R&D Talents
Wanhua Chemical Group Co., Ltd., a public companyheadquartered at the
beautiful coastal city of Yantai, one of “the Most Charming Cities in China
”, specializes in R&D, production and sales of MDI and related products
such as modified MDI, polyether,aromatic polyamine, TPUand CASE products.As
Asia’s largest supplier of MDI products and the world’s second largest
producer of isocyanates, WanhuaChemicalhas operations in Asia, Europe and
America. In 2013, Wanh... 阅读全帖 |
|
s**h
发帖数: 203 | 35 刚在wiki看到
There are seven classes of plastics used in packaging applications. Type 7
is the catch-all "other" class, and some type 7 plastics, such as
polycarbonate (sometimes identified with the letters "PC" near the recycling
symbol) and epoxy resins, are made from bisphenol A monomer.
Type 3 (PVC) can also contain bisphenol A as an antioxidant in plasticizers.
Types 1 (PET), 2 (HDPE), 4 (LDPE), 5 (polypropylene), and 6 (polystyrene) do
not use bisphenol A during polymerization or package formi |
|
G**i
发帖数: 99 | 36 No clinical or research evidence prove the silver material (amalgam) had
mercury toxicity. This material is much better than white material (
composite). There are also some arguement about composite material release
some toxic monomer, but still no clinical or research evidence. Since the
primary molar will be replaced till 11-12 years old. It is better to use
silver material. |
|
s******r
发帖数: 7 | 37 以下是帮忙转发，单位挺实际的，看大家志向和兴趣。
Wanhua Chemical Recruiting R&D Talents
Wanhua Chemical Group Co., Ltd., a public companyheadquartered at the
beautiful coastal city of Yantai, one of “the Most Charming Cities in China
”, specializes in R&D, production and sales of MDI and related products
such as modified MDI, polyether,aromatic polyamine, TPUand CASE products.As
Asia’s largest supplier of MDI products and the world’s second largest
producer of isocyanates, WanhuaChemicalhas operations in Asia, Europe a... 阅读全帖 |
|
u***s
发帖数: 591 | 38 ☆─────────────────────────────────────☆
monomer (单体) 于 (Thu Oct 26 09:28:11 2006) 提到:
I am really pissed by my attorney.
1。 刚开始送evaluate的时候，非常热情，一天两个电话。
2。 等把钱交了，基本上就开始忙了。一般找不到人，发email回的很快，基本上是
说，我会看你写的letter, 下个星期给你。
3。 最后说说，律师所说的polish,基本上是没有怎么动，我的书面英语应该算不错的，
真是很难想象律师能做什么。
我自己的情况是毕业一年，大概14篇左右的文章，80多的citations,
我刚开始办niw,由于有点着急，所以不想自己diy,所以找了律师，
这个律师口碑算不错的，但是我还是觉得他/她很不负责任。
我有几个问题问问大家。
1。 律师到底在哪方面起作用？修改推荐信？修改的幅度有多大？
我给it的几封推荐信返回给我的时候，基本上没有动，
只是加了一些comments, 给了个句子的头。
如果律师说 |
|
u***s
发帖数: 591 | 39 ☆─────────────────────────────────────☆
needniw (needniw) 于 (Wed Jan 3 17:22:03 2007) 提到:
假如我的推荐信都是写给 NSC 的。如果 efiling 让我把材料寄到 TSC, 要该推荐信的
抬头么
☆─────────────────────────────────────☆
monomer (单体) 于 (Wed Jan 3 17:46:56 2007) 提到:
不需要immigration title.
☆─────────────────────────────────────☆
needniw (needniw) 于 (Wed Jan 3 18:01:05 2007) 提到:
前面刚看到有人说要把特定的中心名写上的呀？ |
|
u***s
发帖数: 591 | 40 ☆─────────────────────────────────────☆
monomer (单体) 于 (Mon Feb 12 08:35:40 2007) 提到:
我Jan. 12 efiling I140, 然后以为要等到i797 form到了以后，才寄材料。
i797一个礼拜后到，我copy了一份，跟其他材料一起寄到tsc,
大概Jan. 23材料被 送到。
刚才看了前面的帖子说必须7天内到，难怪我的状态总是下面的内容，
Current Status: Case received and pending.
On January 12, 2007, we received this I140 IMMIGRANT PETITION FOR ALIEN
WORKER
, and mailed you a notice describing how we will process your case. Please
follow any instructions on this notice. We will notify you by mail when
we make |
|
c*******g
发帖数: 1048 | 41 我不想review了，谁有兴趣的请把简历email到[email protected]/* */ 谢谢
Title: The Solvothermal Synthesis of the Cobweb-like WO3 and its Enhanced
Gas-sensing Property Ref. No.: MLBLUE-D-16-04908
Dear Dr xxx,
I am inquiring as to whether you would be able to referee the above short
manuscript, which has been submitted for publication in Materials Letters.
Please note that Letters are very short, i.e. 4 journal pages maximum, so
expect to spend less time than you would to review a regular length article.
In ad... 阅读全帖 |
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i***l
发帖数: 468 | 42 【 以下文字转载自 Military 讨论区 】
发信人: xiaoxiaoxi (小小溪), 信区: Military
标 题: Re: 全美英特尔科学奖决赛名单公布 13名华裔入围
发信站: BBS 未名空间站 (Sat Jan 24 16:00:54 2015, 美东)
Intel STS 2015 Finalists
Anandapadmanaban, Eswar
Dr. Ronald E. McNair Academic High School, Jersey City, NJ
The ThereNIM: A Touch-less Respiratory Monitor
Ashkin, Emily Lorin
Providence Day School, Charlotte, NC
A Novel Synergistic Approach for Enhancing Immunotherapy in the Treatment of
Melanoma
Chemparathy, Augustine George
Dougherty Valley High School, Sa... 阅读全帖 |
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Y**i
发帖数: 3016 | 43 epoxy是个啥？
Epoxy or polyepoxide is a thermosetting polymer formed from reaction of
an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of
applications, including fiber-reinforced plastic materials and general
purpose adhesives.
Epoxy is a copolymer; that is, it is formed from two different
chemicals. These are referred to as the "resin" and the "hardener". The
resin consists of monomers or short chain polymers with an epoxide group
at either end. Most common epoxy resins are prod |
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o******g
发帖数: 10263 | 44 i think it's some special initiator works at room-temperature
some monomer features self-initiation, but it usually starts slow and
accelerates once the visicosity increases to some point |
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i******e
发帖数: 171 | 45 钟表零件，呵呵，又是一个例子。这个例子和生命物质进化的
关键不同之处在于有些零件即使随机搭在一起了，也没有优势，随后
也会被随机拆散。对于多肽，RNA却不是这样。它们都有个能量障碍，
一旦聚合后再拆开，比随机的概率要小的多得多－－accumulation. 而
其它什么各种零件是没有这种特性的，这种幼稚的例子可以休已。
如果早期产生的是有酶活性的小分子多肽，或更可能是小分子RNA
（你知道有些RNA有催化活性的吧， 这是目前知道的保留至今的最
简单的酶）， 而且这个酶活性是复制，那么在monomer浓度足够高
的地方，只要产生一个这样的活性分子， 从那一刻起，以后的生命
物质都将是指数增长－－proliferation/reproduction，各种机裓零
件更是不可能有的特性。
举个例子，科学家们发现比如离海岸一段距离的潮汐池溏就是一种理想
的地方， 海水把原料带进池塘，退潮后水份蒸发，周而复始，用不了多久，
原料浓度就会很高。
考虑到这两个特性，有优势的成果都会被积累，扩散。总而言之，生命物
质的进化总体而言是单向的，而不是简单的随机过程。那些算
出来的概率基本上是一开始就跑题。其 |
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a**********e
发帖数: 418 | 46 Withdraw the first question. It's not valid.
Before making further discussion on how simple organic molecules formed in
the beginning, I would like to clarify the follow assumpion: My
understanding of nature or primitive stage of earth contained a bunch of
simple inorganic molecules, there should be no or very little organic
molecules that are key components of our body. And chemical reactions were
only able to occur to a certain degree. The primitive conditions could not
even get anywhere close... 阅读全帖 |
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a**********e
发帖数: 418 | 47 Let me rephrase my words.
All the biological process have to abide the law of chemistry.
It does not matter what the origin of a biological process or how it began,
you can say RNA, protein, sugar, or whatever. You get to explain how these
molecules formed in nature in the first place.
Please do not just Wiki some topic, and then post it here because a lot of
them have erroneous messages. The belowing so call "well-known" Miller
experiment did not reproduce the samwe amino acids in our body. I ... 阅读全帖 |
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a**********e
发帖数: 418 | 48 Please do some research and find out what amino acids were made in the
experiment and comment again.
---are you considering these amino acids are the same as what are in our
body? Otherwise we would have a (L,S) body instead of L body
well I can assure you the lab symmetric and assymetric synthesis of amino
acid is well known. One of them is strecker synthesis I happened to work on
one of the project. I can purify the amino acid to any degree of purity
you want by different means. So please b... 阅读全帖 |
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R******d
发帖数: 5739 | 49 Please do some research and find out what amino acids were made in the
experiment and comment again.
---are you considering these amino acids are the same as what are in our
body? Otherwise we would have a (L,S) body instead of L body
--------------------------------------
please be specific on what you are refering to. if you are refering to the
stereogenicity, then you are correct. chirality is one of the unsolved
mystery. However, it is only unsolved at this time. It has nothing to do
wit... 阅读全帖 |
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a**********e
发帖数: 418 | 50 同意LZ的概率计算是建立在错误的基础上的
Water is one of the major components on earth. Formation of peptides should
not happen under these conditions. The hydrolysis of the peptides, if by any
chance formed, will dominate. If there were any "natural" amino acids ever
existed, they had to be monomers. I highly doubt there would be a chance to
form a di or tri peptide by nature, not mentioning the complicated
polypeptide structure. |
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