d********i
发帖数: 47 | 1 最近刚刚开始ORIENRATION,第二天考了PBDS,没有达标.还要再考.有哪一位XDJM有 PBDS
的考试资料?
多谢了! |
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d********y
发帖数: 176 | 2 【 以下文字转载自 Biology 讨论区 】
发信人: davidcrazy (haha), 信区: Biology
标 题: 怎样从pbd文件计算一段a-helix的orientation angle (转载)
发信站: BBS 未名空间站 (Mon Apr 9 21:04:09 2007)
发信人: davidcrazy (haha), 信区: Chemistry
标 题: 怎样从pbd文件计算一段a-helix的orientation angle
发信站: BBS 未名空间站 (Mon Apr 9 21:03:41 2007)
有pdb的蛋白质结构,想要决定其中一段a-helix的角度.假设就以pdb文件的分子坐标作
为坐标系.我现在的很粗略的方法就是把那段a-helix所有Ca的坐标提取出来(比如用
excel),然后就直接利用矢量计算.比如第一个Ca的坐标是(x1,y1,z1),第n个Ca的坐标是
(xn,yn,zn),两者构成的矢量就是(xn-x1,yn-y1,zn-y2).然后可以利用基本的三角公式
算出该矢量的tilt angle和azimuthal angl |
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a****a
发帖数: 154 | 4 【 以下文字转载自 HUSHI 俱乐部 】
发信人: amisha (amisha), 信区: HUSHI
标 题: 请问哪位前辈考过PBDS？
发信站: BBS 未名空间站 (Wed Jul 6 17:00:44 2011, 美东)
需要考这个，但可参考的来源实在是少之又少，一个同事几个月前fail过，想请问这里
谁有成功经验可以教一下？ |
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w********h
发帖数: 12367 | 5 molecular weight of your PS-PIP?
if higher than 100K, for sure in semi-dilute.
You can refer to Fetters' review article (Macromolecules 1994, 27:4642) to see
the /M values for PS and PIP.
0.675 for PIP, 0.434 for PS.
Suppose they are the same, say, 0.5.
It is almost half of PBD I am working on.
so, you can predict the overlapping concentration for PS-PIP is about 2.5
times that for PBD for the same Molecular weight.
From Colby's paper for PBD, (Macromolecules 1991, 24, 3873)
0.25 wt.% in g |
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S*****n
发帖数: 6055 | 6 各位老大，请教个问题
俺想做个PS-PBD的胶束，选择用hexane做溶剂，希望能弄点胶束出来玩。现在尝试了两
种block copolymer，一个diblock，一个SBS，其中PS的含量都在20-25%，但是发现，
polymer都无法溶解，只能溶胀。。。
想请教一下，如何能实现我的目标呢？
现在有两个想法，一个是继续降低PS的含量，不知道有没有可能溶解？hexane应该是PS
的不良溶剂，但是可以溶解PBD
再一个是再找个PS的良溶剂，跟hexane混起来溶解copolymer，然后把另外一种溶剂除
掉，看看能不能得到PS-PBD的胶束。但是这另外一种溶剂选什么合适，还在琢磨。。。
三年来，除了这个版面，没有看过跟polymer有关的任何东西，都快忘光了。。。问题
比较弱，大家多排砖，多谢！ |
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d****g
发帖数: 164 | 7 Good job! Wonderlich tongxue gave a clear explanation from the standpoint of
polymer dynamics. But I feel that you are still talking with different
languages. I have seen some rubber processing because my graduate lab in china
mainly worked on rubber, hope I can bridge your gap somehow.
Virgin PBD Rubber itself is thermoplastic before adding crosslinking agent
such as S. But PBD chains is crosslinked after the thermal processing with the
reaction of crosslink agent, thereafter it is thermoset. B |
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s****e
发帖数: 2934 | 8 这个PS-PBD的micelle难道没有文献吗？先查文献用什么样的分子量和怎么用溶剂。PBD貌似会交联，注意保存。形成micelle貌似要好多天。还要不停的搅，对了，还有浓度也是个问题，你看到溶胀是不是就是溶质太多了？
Solution Properties of Diblock Copolymers of Polystyrene-block-polybutadiene
这个文章有用吗
dibutyl phthalate是PS的选择性溶剂，把DBP和benzene混起来再把benzene挥发就得到micelle了。
PS |
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w*****r
发帖数: 11 | 9 PS-PBD也可
但PS-PBD两个嵌段都比较惰性，不如PVP or PAA 容易功能化
另外，我也在考虑使用已经工业化的SBS, ABS等共聚物
但是它们的分子量分布可能会比较大；而且据说一大部分是共混物 |
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发帖数: 1 | 10 海湾战争之前，F-117A 没有经历过像模像样的实战检验，飞行员对“夜鹰”在伊
拉克上空会遭遇到什么样的情况心里没底。因此他们在训练中有意要试试伊拉克防空系
统的反应。当 F-117A 飞近伊拉克边界，伊拉克雷达没有任何反应；而当非隐形飞机来
到同样空域时，伊方雷达则立即作出反应。这一试验结果让“夜鹰”的飞行员们踏实了
很多。
在“沙漠风暴”行动中，多国部队的飞机面对了来自伊方的三种威胁：战斗机、高
炮和地空导弹。战时巴格达的防空火力密集到在F-117的座舱内都能闻到火药味。一位
驾驶“夜鹰”的飞行员说：“没想到我能从这片恐怖的火网中穿出去，炮火太猛烈了。
我看见前前后后到处都是防空导弹。它们不断从我的航线上穿过，幸运的是，没有一枚
锁定我的飞机！”有几次，F-117A 飞临巴格达上空时，与在空中巡逻的伊方米格战斗
机相距很近，竟然未被发现。最惊险的一幕是，1 月 17 日晚，一架执行轰炸巴格达任
务的 F-117A 从两架迎面飞来的米格-23 中间飞过竟未被对方察觉。
“夜鹰”战斗机在其服役生涯中，先后参加过入侵巴拿马、海湾战争、科索沃战争
、伊拉克战争等不同规模的局部战争。尽管参加... 阅读全帖 |
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w**k
发帖数: 6722 | 12 这里都是ETF
发包子吧
AADR AAIT AAXJ ACIM ACWI ACWV ACWX ADRA ADRD ADRE ADRU
ADZ AFK AGA AGF AGG AGLS AGND AGOL AGQ AGZ AGZD AIA
AIRR ALD ALFA ALTS AMJ AMLP AMPS AMU AMZA AND ANGL
AOA AOK AOM AOR ARGT ARKG ARKK ARKQ ARKW ASEA ASHR
ASHS AUNZ AUSE AXJL AXJS AXJV AYT AZIA BAB BABS BAL
BAR BBC BBH BBRC BCHP BCM BDCL BDCS BDD BFOR BIB BICK
BIK BIL BIS BIV BIZD BJK B... 阅读全帖 |
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l****r
发帖数: 665 | 13 我想知道pbd文件能转换成什么文件isilo还需付费不算合适 |
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t********k
发帖数: 808 | 14 一个天杀的把硬盘FORMAT了,上面有一些重要的PowerBuilder文件PBL,
用DOS 622上的UNFORMAT恢复不行,怎么办?
另外,有能使EXE,PBD转到PBL类型的工具么?
系统是Windows 98 第二版. |
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n******7
发帖数: 12463 | 15 大致搜了一下，似乎没有什么general的研究，都是focus到具体某个蛋白
不知道PBD里面一个gene多个isoform都有结构的多不多
麻烦指点一二 |
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w********h
发帖数: 12367 | 16 恩，是这个样子。偶曾经用过PMA，将甲苯抽去后剩下白色弹性粘稠物，
它是rubber-like，而不是PMMA的玻璃态，而且这种rubber并不象PBD,
,PIP,PDMS一样痛痛快快就可以团在一起（Mw>Me)或者粘稠流质（Mw~
所以特别讨厌，不如给溶了算了。 |
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s*****n
发帖数: 430 | 17
en, our hydrogenation process is like this:
catalyst system:
a. Palldium 5% on CaCO3 (about 25%wt in polymer)
b. Wilkinson's catalyst: Chlorotris (triphenyl phosphine) rhodium (I)
(about 3.5%wt in polymer)
temp. around 65C
H2 not higher than 400 psi, even lower, but it may need more time
but this's for PBd.
you can monitor the reaction by checking = with FTIR. |
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w********h
发帖数: 12367 | 18 我的低分子量的PBD(Mw=2K)GPC结果显示含有少量高分子量的东西（分子量大约60K)，
如何除去？我只要一点点纯的2K（大约0.5g)就可以了.过柱子这种方法就算了，我
等不及，最好是什么不同溶剂分几次的方法。什么溶剂比较好呢？toluene+环己烷？ |
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y****u
发帖数: 50 | 19 If I were you, I would rather do the synthesis again :)
living anioic polymn of PBD should be easy...even though I have no experience. |
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y****u
发帖数: 50 | 20 then ask Quirk to do it again
he won't fail you :P
我的低分子量的PBD(Mw=2K)GPC结果显示含有少量高分子量的东西（分子量大约60K)
？ |
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w********h
发帖数: 12367 | 21 low molecular weight?
for 1,4-PBD, i know it happens for low molecular weights.. |
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w********h
发帖数: 12367 | 22 PBD -100C,
PIP -65C
what polymer do you have? |
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w******r
发帖数: 43 | 23 what is your means about phase diagram?
Block copolyme can form different morphologies in dilute solutions.
With increase of concentration, the micelle solution could be BCC, FCC
structure. TPL has some papers about the characterization and kinetic
transition between BCC<>FCC.
Bates reported various micelle morphlogoies formed
from PBD-PEO diblock copolymers. They did a lot of cryoTEM and got very nice
images.
(1) Jain, S.; Bates, F. S. Science 2003, 300, 460.
(2) Won, Y.-Y.; Brannan, A. K.; Dav |
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w********h
发帖数: 12367 | 24
MODING加工，有没有什么POLYMER在室温甚至0C的
low Tg..
PIP, -60
PBD, -100
then that molecular weight is still useful? |
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w********h
发帖数: 12367 | 25
temperature
PIP and PBD surely are solid at room temperature..
I think the answer is yes. But I don't know this part in detail. |
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b**m
发帖数: 18 | 26
Is PBD polybutadiene? Is it the official name of rubber? How come rubber (not
thermoplastics) can be extruded...? Thanks a lot. |
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w********h
发帖数: 12367 | 27 hehe, you must be in polymer engineering.
our languages are quite different.
my understanding is this:
your crosslink density is my entanglement molecular weight Me,
the lower Me, the higher crosslink density.
when Me=M0 (monomer molecular weight), it is crosslinked (also called
thermoset). is that right?
PS Tg=100C Me=18000g/mol
PBD Tg=-100C Me=1543g/mol
PS is normally glass-like (or thermoplastic) at room temperature because of
its high Tg.
When you increase your temperature to 130 to 150C,
yo |
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w********h
发帖数: 12367 | 28
china
the
yes. I am not talking about crosslinked (even slightly crosslinked) PBD.
yes, viscoelasticity.
of |
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w********h
发帖数: 12367 | 29 don't quite understand your question here.
you mean a particular case or a general one?
natural polymers are not necessarily hydrophilic,
or much higher molecular weight.
PEG, PGA are hydrophilic.
while normal natural rubber (PBD and PIP) is hydrophobic.
there are not many pairs of miscible blends. |
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w********h
发帖数: 12367 | 30 pure 1,2-PBD? The name of that is PVE, poly(vinyl ethylene).
Tg is around 0 degree C.
however, it has a very strong dependence on 1,2-content.
refer to Carella, Graessley, and Fetters, Macromolecules 1984, 17, 2775. |
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S*****n
发帖数: 6055 | 31 呵呵。。。
我的题目的要求是把这些东西溶解在hexane里面，不能用其他溶剂或者混合溶剂。。。
至于形成啥样的micelle，甚至能否形成micelle，倒是不在乎。。。
PBD貌似会交联，注意保存。形成micelle貌似要好多天。还要不停的搅，对了，还有浓
度也是个问题，你看到溶胀是不是就是溶质太多了？
polybutadiene
到micelle了。 |
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w********h
发帖数: 12367 | 33 这个你要查了，
要是PBD和PS，还是颇有几篇经典文献供你参考，呵呵 |
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g***e
发帖数: 584 | 34 来自主题: Macromolecules版 - 求助文献 题目是：SYNTHESIS AND CHARACTERIZATION OF PS-PI AND PS-PBD RANDOM COPOLYMERS
AND
RANDOM-DIBLOCK COPOLYMERS VIA ANIONIC POLYMERIZATIONS
作者：SMITH SD, ASHRAF A, CLARSON SJ
来源出版物: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 卷: 206
页: 387-POLY
子辑: Part 2 出版年: AUG 22 1993
非常感谢！ |
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b*****6
发帖数: 111 | 35 因为人在德州，正在申请德州的IM 和 FM。从一个FM program director 听说德州医生
协会最近有个名单，只有名单上合格的学校才有认证资格，才可以在德州做住院医。他
给我的名单上中国无一所医学院校合格。请看附件。按此类推，我们就全部无法申请德
州的program了。请大家核实并求助。
附件好像粘不上。有30页呢。贴下面吧。大家不要嫌长。总之所有学校都有代码。台湾都有几所在名单上。但是大陆一所没有。怎么办！！！！！
Schools Whose Graduates Do Not Have To Prove
Substantial Equivalence Of Their Education
100 ALABAMA
102 UNIV OF ALABAMA SCH OF MED, BIRMINGHAM
104 BIRMINGHAM MED COLL, BIRMINGHAM (EXTINCT)
106 UNIV OF SOUTH ALABAMA COLL OF MED, MOBILE
300 ARIZONA
301 UNIV OF ARIZONA COLL OF MED, TUC... 阅读全帖 |
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J*****N
发帖数: 21 | 36 对不起，各位，几天没来了。 回帖晚了点。Just passed drug test on the 3rd day
of orientation. We were told that all new employees (bedside RNs) have to
take and pass PBDS test. OMG, never thought we still have to take test after
NCLEX. Anyway, working on it. Don't remember who mentioned NCSBN above, Yes
I used it as well. Since our school bought the code for us (used our
tuition though, lol).
@ someone above who mentioned books, yes I do have them here now. I was
going to put them on Ebay to sell,Haven't start list... 阅读全帖 |
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