S********o
发帖数: 368 | 1 首先do direct injection，相同浓度的样品进个5针10针，看看是不是仪器坏了
如果仪器没有问题的话，那么就是SPME部分。
首先好好condition一下fiber。
然后试着延长一下desorption time或者提高desorption temperature。
也可以考虑换个其他coating的fiber试试看
有可能是你的sample里面有啥成分跟你的fiber coating作用非常强，无法完全解吸附
下来
导致fiber coating的available sites减少。
也有可能是fiber coating的损失。可以考虑换个新的，相同coating的fiber。
ps：个人觉得跟柱子没有啥关系。 |
|
c*****a
发帖数: 3965 | 2 我觉得你可以用一个简单的方法测试一下到底是spme吸附的问题，还是desorption的问题
你用methylene chloride把吸附过VOC的管子（我不知道具体是什么）洗一下，我估计
里面的VOC都会到MC里，然后你用针注射含有VOC的MC到GCMS，重复几次，如果还是不一
致，就是吸附时出的问题
如果结果是一致的，那么应该就是GCMS desorption过程有什么地方不对，比如时间设
置什么的
我还是建议你搞一个气路进样的装置，pump可以一直开着，流量很小，不怎么影响气袋
体积 |
|
m***n
发帖数: 266 | 3 来自主题: Macromolecules版 - 紧急求助 drug delivery
monolithic system. dissolved active drug in matrix
desorption of drug can be expressed as early time and late time.
desorption from a slab with thickness of l can be expressed by
two series, which is derived in Crank's book "mathematics of diffusion".
现在找不到这本书，下周一需要交推导过程。哪位知道如何从建立模型到推出这
两个series的表达式。
大致为： Mt/Mo=1- infinite
__
\ 8exp[-D(2n+1)super2paisuper2t/l2}/(2n+1)2pai2
/__
没法表示清楚这个公式。大致意思吧。多谢多谢！ |
|
b**s
发帖数: 589 | 4 Adsorption can happen due to any type of force, but according to 惰性气体
分子 , yes, Van der Waals force is the reason
是不是温度越低,这个force的作用越大
yes, adsorption - desorption is a kinetic process, the lower the
temperature, the less active of the gas molecules, then the lower rate of the
desorption |
|
|
f**x
发帖数: 4325 | 6 世界上哪个单项科研成果不是“就那么回事儿”？
下面这些又牛逼了多少？怎么就不是“就那么回事儿”了？
The Nobel Prize in Chemistry 2014
Eric Betzig, Stefan W. Hell and William E. Moerner
"for the development of super-resolved fluorescence microscopy"
The Nobel Prize in Chemistry 2013
Martin Karplus, Michael Levitt and Arieh Warshel
"for the development of multiscale models for complex chemical systems"
The Nobel Prize in Chemistry 2012
Robert J. Lefkowitz and Brian K. Kobilka
"for studies of G-protein-coupled receptors"
The Nobel Prize in Chemist... 阅读全帖 |
|
z*h
发帖数: 773 | 7 In China, some expert did very detailed analysis. The push power is from gas
desorption from the surface. NASA experiment was done under low vacuum
conditions. So NASA persons are stupid, again. Under high vacuum conditions,
no such thing will be observed. |
|
M****o
发帖数: 4860 | 8 大家来分析一下，哪些是1作，哪些是通讯，哪些是酱油？
PUBLICATIONS since 2007
1. Q. Zhou, Z. Zhao, Y. Chen, H. Hu, J. Qiu, Low temperature plasma-mediated
synthesis of
graphene nanosheets for supercapacitor electrodes, J. Mater. Chem., 2012, in
press, doi:10.1039/C2JM15572A.
2. J. Liu, L. Yu, Z. Zhao, Y. Chen, P. Zhu, C. Wang, Y. Luo, C. Xu, A. Duan,
G. Jiang,
Potassium-modified molybdenum-containing SBA-15 catalysts for highly
efficient production of acetaldehyde and ethylene by the selective oxidation
of ethane, J. Cata... 阅读全帖 |
|
s******e
发帖数: 34 | 9 The Energy, Environment and Infrastructure (E2I) Business Unit of Science
Applications International Corporation (SAIC) is seeking a qualified
Computational Scientist for the role of molecular and continuum dynamics
modeler.
Job Description: The incumbent must possess 7+ years of related experience
and a BS or equivalent degree (MS or Post-doc preferred) in chemistry,
biochemistry, biomolecular engineering and/ or have a background in modeling
of biological system on a molecular level. Backgroun... 阅读全帖 |
|
l*****8
发帖数: 16949 | 10 吐这种酸水没意思。看看他的文章。如果你不是在大学混的，可以原谅。
PUBLICATIONS since 2007
1. Q. Zhou, Z. Zhao, Y. Chen, H. Hu, J. Qiu, Low temperature plasma-mediated
synthesis of
graphene nanosheets for supercapacitor electrodes, J. Mater. Chem., 2012, in
press, doi:10.1039/C2JM15572A.
2. J. Liu, L. Yu, Z. Zhao, Y. Chen, P. Zhu, C. Wang, Y. Luo, C. Xu, A. Duan,
G. Jiang,
Potassium-modified molybdenum-containing SBA-15 catalysts for highly
efficient production of acetaldehyde and ethylene by the selective oxidation
of ethane, J... 阅读全帖 |
|
p*****r
发帖数: 805 | 11 Elsevier的材料类杂志， IF~2.3左右。
关键词：Mesoporous silica materials（MCM-41）， X-ray diffraction, N2
sorption/desorption, scanning electron microscopy(SEM), transmission
electron microscopy(TEM)
有意者请回复或者站内联系，先到先得，包括你的name，email(institutional or
professional email prefer),list of publications（包括文章的title）给我, 如果
背景合适我会向杂志编辑推荐。如果你得到了审稿机会，希望秉持专业精神按时保质保
量完成。 |
|
g******h
发帖数: 101 | 12 A journal in analytical chemistry area, IF= ~4
about application Laser Desorption-Ionization Mass Spectrometry
Please send me your brief research summary and resume. I can recommend you
to the editor if it matches your background. |
|
w*****g
发帖数: 125 | 13 GONE
manuscript from European Journal of Mass Spectrometry, on DIRECT LASER
DESORPTION/IONIZATION OF PHOSPHOPEPTIDES
PM me if interested with your CV. |
|
C********7
发帖数: 1035 | 14 关键词：TiO2-SiO2 nanocomposites, mesoporous structure, templated synthesis,
scanning electron microscopy (SEM), transmission electron microscopy (TEM),
X-ray diffraction (XRD), N2 adsorption and desorption, UV-vis.
Materials Science Journal
Impact factor ~ 2.3
Send me your name, email, affiliation, list of publications,a couple
sentences describing your expertise. Candidate with matching background and
earliest correspondence will be recommended. |
|
y******u
发帖数: 1123 | 15 关键词
illicit drugs， biological fluids，desorption/ionization mass spectrometry，
nanoporous silicon microparticles
杂志
ACA，分析类算top
感兴趣的给我姓名，单位，邮箱和简单背景。希望背景相关，不然推荐也没用。 |
|
R********a
发帖数: 467 | 16 专家终于出现了。大哥您今年去AICHE的话，请提前打个招呼。我准备一路讨饭过来见
您啊。我有几个问题，您老能详细解释一下吗？
ac吸附的原理大概是什么？什么条件下容易adsorption，什么条件下容易desorption.
bioactivity不一样的原因是什么？ |
|
r****o
发帖数: 105 | 17 本文献给YL
（二十一）离子交换层析
做完硫酸铵沉淀以及等电点沉淀之后，下一步就是做离子交换层析
(ion-exchange chromatography)。离子交换层析原理很简单，利用蛋
白质表面的带电基团和resin上带相反电荷的ion exchanger group相互结
合来纯化蛋白。离子交换柱和affinity chromatography一样，属于
absorption/desorption型的层析方法，与gel filtration完全不一样，其中
一个最大的优点是，样品体积可以很大，最后的洗脱样品的体积可以小很
多，这样实际起到了一个浓缩样品的作用。还有一个优点是，离子交换层
析其实不需要柱子，可以用batch 的方法（在离心管里面混合beads和样
品）。当然如果beads量多情况下，batch方法平衡得不是很好，导致
resolution不是很好。这一点我们做实验的时候深有体会，以后的一篇中我
会提到。我们纯化钙调蛋白用了柱子做纯化，原因是因为所用的beads 相
当于Sephadex G-50再加上阴离子交换基团，所以实际上可以看成是 |
|
e**e
发帖数: 166 | 18 ANALYSIS OF CARBOHYDRATES AND GLYCOCONJUGATES BY MATRIX-ASSISTED LASER
DESORPTION/IONIZATION MASS SPECTROMETRY: AN UPDATE FOR 2009-2010
Author Full Names:
Harvey, David J.
Source:
MASS SPECTROMETRY REVIEWS, 34 (3):268-422; 10.1002/mas.21411 MAY-JUN 2015
Please send to [email protected]
/* */
thank you very much. |
|
|
s*******c
发帖数: 133 | 20 一般在impregnation之前，会用蒸馏水测试载体的饱和孔体积，不知道lz试了没有？是
否就是你说说的pore volumn，采用N2-adsorption-desorption测得与前一个不一样。
一般金子完之后，会在旋转蒸发仪礼vapor，不知道你是怎么桌的？
另，不知道Ca（Ac）2在水中常温的溶解度如何？
有很多可能 |
|
j******7
发帖数: 137 | 21 https://erecruit.pnl.gov/psp/hrext/EMPLOYEE/HRMS/c/HRS_HRAM.HRS_CE.GBL
Position 1
Job Title:
Post Doctorate RA - Chemical Physics
Job ID:
300312
Location:
PNNL - Richland, WA
Return to Previous Page
Organization and Job ID
Job ID: 300312
Directorate: Fundamental & Computational Sciences
Group: Chemical Physics & Analysis
.
Job Description
This position is in the area of dynamics and kinetics of th... 阅读全帖 |
|
r********g
发帖数: 402 | 22 Examination of complex oligosaccharides by matrix-assisted laser
desorption/ionization mass spectrometry on time-of-flight and magnetic
sector instruments
Organic Mass Spectrometry
Volume 29, Issue 12, pages 753–766, December 1994
万分感谢。 |
|
|
s****y
发帖数: 62 | 24 实验一直出不来稳定的结果，所以想在这里看看有没有人做同样的方向，能够给我一些
意见。
实验室里有一个5.5立方米的气袋，我的实验是：每次用syringe 吸取一定量的a-
pinene 或者是
limonene，大概是8uL或者是16uL，然后让干净的流动空气带着挥发的有机物进入气袋
。每次我大概让空
气充气袋40分钟-1个小时左右。（当然，提前先抽空一部分气袋，大概抽空20%左右）
。 这样气袋里面就充
满了带有样品的气体。当然这个时候，气袋是密封住的。所有的开口都关上。
然后我用tube连上泵，泵就以5L/min的速度从气袋里面抽空气流过tube。我就把SPME
fiber放在tube的
中间，然后让流过的样品空气，这样SPME就把样品吸附上去。
我的采样时间是2分钟。然后立刻用GCMS去分析样品。
采样条件
Experiment condition :
Temperature : room temperature
Flow rate : 5L/min
Sampling time : 2min
GC desorption time 5min @ 300℃
但是每次我的GC出来的峰面... 阅读全帖 |
|
|
b*******g
发帖数: 1309 | 26 一般都是高强度激光，普通光不容易把
波长方面，查一下 TAMU 的 David H Russell 文章，他们有一篇 visible light
532nm AuNR desorption 的文章，不过测的应该不是monolayer，是小分子or peptide
看你是做环境的，这些好像跟你都没关系。。。。。。
吧！ |
|
j******7
发帖数: 137 | 27
https://erecruit.pnnl.gov/psp/hrext/EMPLOYEE/HRMS/c/HRS_HRAM.HRS_CE.GBL
Job Title:
Post Doctorate RA - Chemical Physics
Job ID:
301027
Location:
PNNL - Richland, WA
Return to Previous Page
Organization and Job ID
Job ID: 301027
Directorate: Fundamental & Computational Sciences
Group: Chemical Physics & Analysis
.
Job Description
The Chemical Physics and Analysis Group at Pacific Northwest Na... 阅读全帖 |
|
t******g
发帖数: 439 | 28 Rapid detection of powdered antibiotics by surface desorption atmospheric
pressure chemical ionization tandem mass spectrometry.
Research Journal of Chemistry and Environment (2010), 14, (1), 11-18.
ISSN:0972-0626.
谢谢！ |
|
b*******g
发帖数: 1309 | 29 http://www.futuremedicine.com/doi/abs/10.2217/nnm.10.127
Title: Nanomaterial-assisted laser desorption ionization for mass
spectrometry-based biomedical analysis
Author(s): Qiao Liang; Liu BaoHong; Girault Hubert H.
Source: NANOMEDICINE Volume: 5 Issue: 10 Pages: 1641-1652 DOI: 10.
2217/NNM.10.127 Published: DEC 2010
please send to b***********[email protected]
thanks a lot! |
|
w******n
发帖数: 13202 | 30 《质谱学报》，2004.B10， page 205-216
Exploring the Potential of Cryodetectors for the Detection of Matrix-
Assisted Laser Desorption／Ionization Produced Ions： Application to
Profiling and Imaging Mass Spectrometry
Pierre Chaurand,Gertraud Hayn,Urs Matter,Richard M.Caprioli,
thanks!
b*********[email protected] |
|
|
|
y****z
发帖数: 92 | 33 Can someone download this paper for me please? Thank you!
Eur J Mass Spectrom (Chichester, Eng). 2003;9(3):213-9
Biotin-enhanced fragmentation for direct deoxyribonucleic acid sequencing
using matrix-assisted laser desorption/ionization mass spectrometry |
|
q*********s
发帖数: 5 | 34 如很多人一样本人也开始准备申请绿卡了，目前在给两三家欧洲期刊审稿（IF 2-4），
但是稿件不多.现请求前辈们推荐更多审稿机会，我的方向是:
1. Mass Spectrometry (Application, new instrument design, etc.)
2. Chromatography (UPLC, HPLC, GC, etc.)
3. Elemental analysis, such as ICP, Glow Discharge, and Laser Desorption;
4. Environmental sample analysis.
本人审稿保证质量和速度，请各位前辈放心。谢谢 |
|
发帖数: 1 | 35 您好，不知道这个职位是否找到合适的人选，我的背景还是比较符合的，PhD期间做了
大量活性炭的工作，之间还在膜分离公司工作过四年有丰富的工程经验，请看我的简历
，如果您觉得还可以的话请与我联系，非常感谢！
Yuhe Cao
North Campus Drive 1400,
Agricultural and Biosystems Engineering,
South Dakota State University,
Brookings, SD 57007
(605) 592-0789
[email protected]/* */
Objective
Challenging research position in membrane science in a pharmaceutical, gas
adsorption, gas purification and separation, water treatment or biotech
company or university
Qualifications
• How fiber membrane fabr... 阅读全帖 |
|
发帖数: 1 | 36 您好，不知道这个职位是否找到合适的人选，我的背景还是比较符合的，PhD期间做了
活性物分离提取的工作，之间还在膜分离公司工作过四年有丰富的工程经验，请看我的
简历，如果您觉得还可以的话请与我联系，非常感谢！
Yuhe Cao
North Campus Drive 1400,
Agricultural and Biosystems Engineering,
South Dakota State University,
Brookings, SD 57007
(605) 592-0789
[email protected]/* */
Objective
Challenging research position in membrane science in a pharmaceutical, gas
adsorption, gas purification and separation, water treatment or biotech
company or university
Qualifications
• How fiber membrane fa... 阅读全帖 |
|
发帖数: 1 | 37 您好，不知道这个职位是否找到合适的人选，我的背景还是比较符合的，PhD期间做了
活性物分离提取的工作，之间还在膜分离公司工作过四年有丰富的工程经验，请看我的
简历，如果您觉得还可以的话请与我联系，非常感谢！
Yuhe Cao
North Campus Drive 1400,
Agricultural and Biosystems Engineering,
South Dakota State University,
Brookings, SD 57007
(605) 592-0789
[email protected]/* */
Objective
Challenging research position in membrane science in a pharmaceutical, gas
adsorption, gas purification and separation, water treatment or biotech
company or university
Qualifications
• How fiber membrane fa... 阅读全帖 |
|
s*****j
发帖数: 96 | 38 ID: shajinj,
Ph.D. Environmental Chemistry and Ecotoxicology
方向：Fate and transport behaviors of organic contaminants in the
environment,including (but not limited to) sorption/desorption, degradation,
bioaccumulation, toxicity, water transfer, etc.
曾经为以下杂志做过审稿：Environmental Science and Technology, Environmental
Toxicology and Chemistry, Journal of Environmental Monitoring,Environmental
Pollution.
谢谢！ |
|
s*****j
发帖数: 96 | 39 ID: shajinj,
Ph.D. Environmental Chemistry and Ecotoxicology
方向：Fate and transport behaviors of organic contaminants in the
environment,including (but not limited to) sorption/desorption, degradation,
bioaccumulation, toxicity, water transfer, etc.
曾经为以下杂志做过审稿：Environmental Science and Technology, Environmental
Toxicology and Chemistry, Journal of Environmental Monitoring,Environmental
Pollution.
谢谢！ |
|
t***w
发帖数: 89 | 40 这里是我的情况，同求审稿，
Environmental Science, PhD,
帐号：tcotw
个人邮箱：z*******[email protected]
研究方向：
- Fate and transport of pollutants.
- Environmental behavior of nanomaterials.
aggregation, sorption/desorption.
- Environmental toxicology.
- Human health risk assessment.
- Soil and groundwater remediation.
发表论文：Environmental Science and Technology, Water Research, Journal of
Hazardous Materials.
审稿经历：Environmental Science and Technolgoy, PLoS ONE.
希望相关方向的同学推荐审稿。 |
|
s****y
发帖数: 62 | 41 实验一直出不来稳定的结果，所以想在这里看看有没有人做同样的方向，能够给我一些
意见。
实验室里有一个5.5立方米的气袋，我的实验是：每次用syringe 吸取一定量的a-
pinene 或者是
limonene，大概是8uL或者是16uL，然后让干净的流动空气带着挥发的有机物进入气袋
。每次我大概让空
气充气袋40分钟-1个小时左右。（当然，提前先抽空一部分气袋，大概抽空20%左右）
。 这样气袋里面就充
满了带有样品的气体。当然这个时候，气袋是密封住的。所有的开口都关上。
然后我用tube连上泵，泵就以5L/min的速度从气袋里面抽空气流过tube。我就把SPME
fiber放在tube的
中间，然后让流过的样品空气，这样SPME就把样品吸附上去。
我的采样时间是2分钟。然后立刻用GCMS去分析样品。
采样条件
Experiment condition :
Temperature : room temperature
Flow rate : 5L/min
Sampling time : 2min
GC desorption time 5min @ 300℃
但是每次我的GC出来的峰面... 阅读全帖 |
|
d****i
发帖数: 360 | 42 【 以下文字转载自 Postdoc 讨论区 】
发信人: dududi (dududu,Fourth grade driver), 信区: Postdoc
标 题: textbook!
发信站: BBS 未名空间站 (Thu Jun 19 19:19:43 2008)
Could you guys recommend a book to me about "Matrix-Assisted Laser
Desorption/Ionization MS"? I need to analyze my mass spectra! Thanks! |
|
m***i
发帖数: 1 | 43 Dear all experts,
I am from chemical engineering field with both chemical industry experience
(like thermodynamics, heat exchager, absorption, desorption, fluid flow, etc
.) and computational chemistry experience (like Molecular dynamics and Monte
Carlo simulations, Gaussian etc). Several days ago, I interviewed a small
startup company. This company is focusing on developing the heat engine
claimed to convert low temperature thermal energy (such as at 373 K) to
electricity. My job will be to he |
|
h*****f
发帖数: 80 | 44 小弟是国内医学背景，对药学不太了解，但因为一直听说pharmaceutics比较好找
industry的工作，而现在有机会接触pharmaceutics,所以想请教内行，帮我比较一下这
两个方向？
1）是Physical and Applied Pharmaceutics：具体做physics of tablet compression
, adsorption and desorption thermodynamics, solution calorimetry, analytical
applications of FT-IR, surface characterization by XPS, and micellar
catalysis.
2）是Drug Delivery（我觉得主要是gene delivery) the synthesis and testing of
carrier systems for targeted gene delivery. studies involve peptide,
carbohydrate and bioconjugate synthe |
|
