共查询到10条相似文献,搜索用时 562 毫秒
1.
WANG Xinping CHEN Zhifang & SHEN Zhiquan . Key Laboratory of Advanced Textile Materials Manufacturing Technology of Education Ministry Department of Applied Chemistry Zhejiang Institute of Science Technology Hangzhou China . Department of Polymer Science Engineering Zhejiang University Hangzhou China 《中国科学B辑(英文版)》2005,48(6):553-559
The increased attention has been focused on the re-searches of soft materials proposed by Pierre-Gilles de Gennes, a Nobel Prize Laureate in Physics. A special issue of “Science” on soft surfaces was published in 2002 to review specific surface properti… 相似文献
2.
Importance of shattering fragmentation in the surface-induced dissociation of protonated octaglycine
Kyoyeon Park Bipasha Deb Kihyung Song William L. Hase 《Journal of the American Society for Mass Spectrometry》2009,20(6):939-948
A QM + MM direct chemical dynamics simulation was performed to study collisions of protonated octaglycine, gly8-H+, with the diamond {111} surface at an initial collision energy E
i
of 100 eV and incident angle θ
i
of 0° and 45°. The semiempirical model AM1 was used for the gly8-H+ intramolecular potential, so that its fragmentation could be studied. Shattering dominates gly8-H+ fragmentation at θ
i
= 0°, with 78% of the ions dissociating in this way. At θ
i
= 45° shattering is much less important. For θ
i
= 0° there are 304 different pathways, many related by their backbone cleavage patterns. For the θ
i
= 0° fragmentations, 59% resulted from both a-x and b-y cleavages, while for θ
i
= 45° 70% of the fragmentations occurred with only a-x cleavage. For θ
i
= 0°, the average percentage energy transfers to the internal degrees of freedom of the ion and the surface, and the energy
remaining in ion translation are 45%, 26%, and 29%. For 45° these percentages are 26%, 12%, and 62%. The percentage energy-transfer
to ΔE
int
for θ
i
= 0° is larger than that reported in previous experiments for collisions of des-Arg1-bradykinin with a diamond surface at the same θ
i
. This difference is discussed in terms of differences between the model diamond surface used in the simulations and the diamond
surface prepared for the experiments. 相似文献
3.
Hong-lin Zhang Yue Zhu Ke Zhang Ting-ting Hou Hai-ying Liu Mao-jin Cui Gan-zuo Li Li Yu 《Journal of solution chemistry》2009,38(2):187-198
The power-time curves of the micelle formation process were determined at four temperatures for a cationic surfactant [cetyltrimethylammonium
bromide (CTAB)] in a non-aqueous solvent [N,N-dimethylformamide (DMF)] by titration microcalorimetry. From the data of the
minimum of the titration point and the area of the power-time curves, values of their CMC and ΔH
m
θ
were obtained. Values of ΔG
m
θ
and ΔS
m
θ
were also calculated according to standard thermodynamic relations. For the cationic surfactant CTAB, the relationships involving
the carbon numbers of the alcohols, the alcohol’s concentration, and the temperature on the CMC, and also the thermodynamic
functions for micellization are discussed. For systems containing an identical concentration of various alcohols, values of
the CMC, ΔH
m
θ
and ΔS
m
θ
increased whereas those of ΔG
m
θ
decreased with increasing temperature. For systems containing identical alcohol concentrations at the same constant temperature,
values of the CMC, ΔH
m
θ
,ΔG
m
θ
and ΔS
m
θ
decreased with increasing carbon number of the alcohol. For systems containing the same alcohol at the same temperature,
the CMC and ΔG
m
θ
values increased whereas ΔH
m
θ
and ΔS
m
θ
decreased with increasing alcohol concentration. 相似文献
4.
We report the evidence for attractive interaction of latex particles which are covered by poly(ethylene oxide) chains. These
particles are suspended in aqueous solutions of ammonium sulfate. The interaction is probed by measurements of the turbidity
of the suspensions up to 70 g/l. Turbidity is insensitive to multiple scattering and allows the static structure factor, S(q) [q=(4πn
0/λ0)sin(θ/2), where θ is the scattering angle, n0 is the refractive index of the medium and λ0 is the wavelength in vacuo], to be determined at small q values. The analysis of S(q) at small q values yields information about possible attraction of the particles. The analysis of the turbidity data furthermore shows
that no aggregation took place in these systems. A weak but long-range attractive interaction was found at ammonium sulfate
concentrations of 0.01 and 0.1 M. The relation of this attractive force to hydrophobic forces is discussed.
Received: 9 March 2000/Accepted: 28 June 2000 相似文献
5.
Juliu Voicu 《Colloid and polymer science》1934,67(2):148-154
Zusammenfassung Die an den in einer vorangehenden Abhandlung aufgestellten Gleichungen der wiederholten Auszüge xp=(x0
p- K) (1−r)pq+K (A) oder xp=Ax(1−r)pq+K (a)θ
p=θ
0
p
−K
θ
)(1−r)pq+K
θ
(B) oderθ
p=A
θ
(1−r)pq+K
θ
(b) angestellten überlegungen betrafen unter anderem die Bestimmung der Parameter Ax, A
θ
, K und K
θ
durch graphische Darstellung. Es wurde auch der auf die Werte von K und K
θ
ausgeübte Einflu?, der durch ?nderung von m, der Menge des Adsorbenten, und von V, des Volumens der L?sung, infolge einer
?nderung in der quantitativen Zusammensetzung des Systems entstand, er?rtert.
Es wurde auf die Verkleinerung von K und K
θ
, die nach einer gewissen Zahl von Auszügen infolge einer zu starken Verdünnung der L?sung des Systems eintreten mu?, aufmerksam
gemacht. Diese Verkleinerung erkl?rt sich aus der Anwesenheit des Koeffizienten a und des Exponenten n der Adsorptionsisotherme
in den Gleichungen
; denn die beiden Werte von α und n sind nur für einen beschr?nkten Konzentrationsbereich praktisch konstant.
Es wurde auch gefunden, da? die Werte vonθ, der Substanzmenge in L?sung, oder von x, der Konzentration in 1 ccm, die nach einem Auszug einer beliebigen Ordnung bestimmt
wurden, den Gleichungen (b) und (a) für die Werte p′ von p, die andere sind als der zum untersuchten System geh?rende Wert,
genügen unter der Bedingung, für K, K
θ
, Ax und A
θ
angemessene Werte zu finden. Die oben erw?hnte Schlu?folgerung gilt auch für p=1. Man erh?lt die beiden Gleichungen x=A′(1−r)q+ K′ (E)θ=A (1−r)q+K′θ, (F) die x undθ, die einer Auszugsordnung q entsprechen, direkt ergeben. Die Parameter A′, A, K′ und K′θ k?nnen graphisch ermittelt werden.
Multipliziert man die Gleichung (F) mit r, dem bei dem Auszug entnommenen Volumteil, so erh?lt man die dem System durch einen
Auszug entzogene Substanzmenge aq: aq=rA(1−r)q−1+ c, (G) wo c=rK′θ.
Am Schlu? der Abhandlung wird auf bestimmte Vorteile der Gleichungen (F) und (G) aufmerksam gemacht.
I. Teil: Kolloid-Z.66, 322 (1934).
übersetzt von E. Lottermoser (Leipzig). 相似文献
6.
S. P. Chen X. X. Meng Q. Shuai B. J. Jiao S. L. Gao Q. Z. Shi 《Journal of Thermal Analysis and Calorimetry》2006,86(3):767-774
A
solid complex Eu(C5H8NS2)3(C12H8N2) has been obtained from reaction of
hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC)
and 1,10-phenanthroline (o-phen⋅H2O)
in absolute ethanol. IR spectrum of the complex indicated that Eu3+
in the complex coordinated with sulfur atoms from the APDC and nitrogen atoms
from the o-phen. TG-DTG investigation provided
the evidence that the title complex was decomposed into EuS.
The
enthalpy change of the reaction of formation of the complex in ethanol, Δr
H
m
θ(l), as –22.214±0.081 kJ mol–1,
and the molar heat capacity of the complex, c
m,
as 61.676±0.651 J mol–1 K–1,
at 298.15 K were determined by an RD-496 III type microcalorimeter. The enthalpy
change of the reaction of formation of the complex in solid, Δr
H
m
θ(s), was calculated as 54.527±0.314 kJ mol–1
through a thermochemistry cycle. Based on the thermodynamics and kinetics
on the reaction of formation of the complex in ethanol at different temperatures,
fundamental parameters, including the activation enthalpy (ΔH
≠
θ),
the activation entropy (ΔS
≠
θ),
the activation free energy (ΔG
≠
θ),
the apparent reaction rate constant (k),
the apparent activation energy (E), the
pre-exponential constant (A) and the reaction
order (n), were obtained. The constant-volume
combustion energy of the complex, Δc
U,
was determined as –16937.88±9.79 kJ mol–1
by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy
of combustion, Δc
H
m
θ,
and standard enthalpy of formation, Δf
H
m
θ,
were calculated to be –16953.37±9.79 and –1708.23±10.69
kJ mol–1, respectively. 相似文献
7.
Geometrical parameters associated with N-H ... N types of hydrogen bonds have been analysed using crystal structure data on
nucleic acids, amino acids and related compounds. Histograms depicting the frequency distribution of N-H ... N length (l) and H-N ... N angle (θ) have been drawn and conclusions on the favoured geometry of such bonds have been arrived at. The
distribution ofl shows a pronounced maximum in the range between 2.9? and 3.0? with an overall average of 2.98 ?. The θ distribution shows
a pronounced maximum for the hydrogen bond angle in the range 0°-10°, with a rapid fall-off in frequency for nonlinear hydrogen
bonds. The frequency shows a cos6θ dependence as compared to cos2θ dependence term used earlier to predict the angular dependence of hydrogen bond potential energy in proteins and polypeptides. 相似文献
8.
D. Y. Kwok A. Leung A. Li C. N. C. Lam R. Wu A. W. Neumann 《Colloid and polymer science》1998,276(6):459-469
Low-rate dynamic contact angles of 22 liquids on a poly(n-butyl methacrylate) (PnBMA) polymer are measured by an automated axisymmetric drop shape analysis-profile (ADSA-P). It is found that 16 liquids yielded
non-constant contact angles, and/or dissolved the polymer on contact. From the experimental contact angles of the remaining
6 liquids, it is found that the liquid–vapor surface tension times cosine of the contact angle changes smoothly with the liquid–vapor
surface tension, i.e. γlv cos θ depends only on γlv for a given solid surface (or solid surface tension). This contact angle pattern is in harmony with those from other inert
and non-inert (polar and non-polar) surfaces [34–37, 45–47]. The solid–vapor surface tension calculated from the equation-of-state
approach for solid-liquid interfacial tensions [14] is found to be 28.8 mJ/m2, with a 95% confidence limit of ±0.5 mJ/m2, from the experimental contact angles of the 6 liquids.
Received: 12 September 1997 Accepted: 22 January 1998 相似文献
9.
G. Xie S. P. Chen S. L. Gao X. X. Meng Q. Z. Shi 《Journal of Thermal Analysis and Calorimetry》2006,83(3):693-700
A novel solid complex, formulated as Ho(PDC)3
(o-phen), has been obtained from the reaction
of hydrate holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and
1,10-phenanthroline (o-phen·H2O)
in absolute ethanol, which was characterized by elemental analysis, TG-DTG
and IR spectrum. The enthalpy change of the reaction of complex formation
from a solution of the reagents, ΔrHmθ (sol), and the molar heat capacity of the complex, cm,
were determined as being –19.161±0.051 kJ mol–1
and 79.264±1.218 J mol–1 K–1
at 298.15 K by using an RD-496 III heat conduction microcalorimeter. The enthalpy
change of complex formation from the reaction of the reagents in the solid
phase, ΔrHmθ(s), was calculated as
being (23.981±0.339) kJ mol–1 on the
basis of an appropriate thermochemical cycle and other auxiliary thermodynamic
data. The thermodynamics of reaction of formation of the complex was investigated
by the reaction in solution at the temperature range of 292.15–301.15
K. The constant-volume combustion energy of the complex, ΔcU, was determined as being –16788.46±7.74
kJ mol–1 by an RBC-II type rotating-bomb
calorimeter at 298.15 K. Its standard enthalpy of combustion, ΔcHmθ, and standard enthalpy of formation,
ΔfHmθ, were calculated to be –16803.95±7.74 and –1115.42±8.94
kJ mol–1, respectively. 相似文献
10.
The magneto-structural correlation between a Mn(ll) ion, coordinated in an octahedral environment, and two nitronyl nitroxide
radical ligands in trans- and cis-metal-radical complexes is investigated by the broken symmetry (BS) approach within density functional theory (DFT).
The dependences of coupling constants J on three structural parameters: (i) bond angle θ (Mn-O-N (nitroxide)); (ii) rotating angle ψ, defined by the nitronyl nitroxide radical plane rotating around the axial Mn-O (nitroxide); (iii) bond distance R (Mn-O (nitroxide)) are directly calculated. Our calculations showed that both trans- and cis-Mn(ll)-radical complexes behave a stronger antiferromagnetic interaction, consistent with experiments. In view of
molecular orbital theory, the direct exchanges, including σ-type and π-type exchanges, are responsible for the magnetic exchange
pathways. There is a preferable linear correlation between the calculated coupling constants J and the overlap integral squares S b between the local magnetic orbitals at the various rotating angle ψ at the fixed bond angle θ and bond distance R, in both trans- and cis-Mn(ll)-radical complexes. 相似文献