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41.
Summary Heat transfer to fibers formed in dry spinning has been subjected to fundamental analysis. Solutions of the equation of energy have been derived and tested with experimental data. Results were deemed satisfactory in view of the accuracy of the experimental data. The present work is believed to yield a good representation of the heat transfer in the dry spinning process.Nomenclature
h
heat transfer coefficient, cal/cm2 °C sec
-
k
thermal conductivity, cal/cm °C sec
-
r
radial distance, cm
-
t
time, sec
-
Z
axial distance, cm
-
A
surface area, cm2
-
A
n
or n-th root of
-
A
0
energy required for solvent evaporation, cal/sec cm3
-
C
p
specific heat cal/gm °C
-
J
0
Bessel function of first kind, order zero
-
J
1
Bessel function of first kind, order one
-
J
2
Bessel function of first kind, order two
-
N
k/(R
2
C
p
V)
-
Q
volumetric flow rate cm3/sec
-
R
outside radius, cm
-
T
point temperature, °C
-
T
S
surface temperature °C
-
T
0
initial fiber temperature °C
-
T
ambient air temperature, °C
-
average fiber temperature, °C
-
1
average fiber temperature of preceding segment, °C
-
V
average fiber velocity relative to air strean, cm/sec
-
V
r
radial velocity component, cm/sec
-
V
z
axial velocity components, cm/sec
-
V
direction velocity component cm/sec
-
W
weight of solvent evaporated in a given fiber segment, gms
-
n
a solution of the equation J
0(X)=0
-
heat of vaporization of solvent, cal/gm
-
dimension
-
r/R
-
density, gms/cc 相似文献
42.
43.
Utilization of Active Ni to Fabricate Pt–Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation
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Dr. Liangfeng Luo Haiyuan Lu Prof. Gang Zhou Prof. Weixin Huang Prof. Xun Hong Prof. Yuen Wu Prof. Yadong Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13181-13185
Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel–aluminum layered double hydroxide (NiAl–LDH) onto a Pt–Ni alloy surface. The incorporation of chemical etching of Pt–Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni‐rich Pt–Ni octahedra transform by interior erosion into Pt3Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt3Ni, the resulting Pt–Ni nanoframe/NiAl–LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural. 相似文献
44.
Atmospheric pressure plasma (APP) treatment was applied as a pretreatment process to enhance the deposition of printing paste
in order to improve the final colour properties of digital ink-jet printed cotton fabrics. Three printing pastes containing
natural polymers, i.e. (1) sodium alginate, (2) chitosan and (3) sodium alginate-chitosan mixture, were prepared separately.
After APP treatment, cotton fabric was padded with different printing pastes prior to digital ink-jet printing. Experimental
results showed that APP pretreatment could increase the colour yield of the digital ink-jet printed cotton fabric significantly
even after washing. In addition, other properties such as colour fastness to crocking, colour fastness to laundering, outline
sharpness and anti-bacterial properties were also improved when compared with those of the control cotton fabric printed without
APP pretreatment. However, the influence of printing paste on the colour properties of the digital ink-jet printed cotton
fabrics depended very much on the composition of the printing paste. The scanning electron microscope images evidenced that
the APP treatment could enhance the deposition of printing paste on the cotton fabric surface as proved qualitatively by both
the contact angle and wetting time measurement as well as quantitatively by both the X-ray photoelectron spectroscopy and
carboxyl group/nitrogen content analysis. 相似文献
45.
Goldstein DC Cheng YY Schmidt TW Bhadbhade M Thordarson P 《Dalton transactions (Cambridge, England : 2003)》2011,40(9):2053-2061
Four new hetero- and homo-leptic iridium(III) bisterpyridine complexes have been prepared which incorporate aniline (tpy-φ-NH(2)), benzoic acid (tpy-φ-COOH), and benzyl alcohol (tpy-φ-CH(2)OH) substituents at the 4' positions of the tpy ligands (tpy = 2,2':6',2'-terpyridine, φ = phenylene). The electrochemical behaviour and ground and excited state spectroscopic properties of the complexes are reported, and the X-ray crystal structures of a homoleptic benzyl alcohol [Ir(tpy-φ-CH(2)OH)(2)](PF(6))(3), homoleptic aniline [Ir(tpy-φ-NH(2))(2)](PF(6))(3), and heteroleptic benzyl alcohol/aniline substituted complex [Ir(tpy-φ-CH(2)OH)(tpy-φ-NH(2))](PF(6))(3) have been solved. Complexes with aniline substituents were found to display absorption bands at around 430 nm corresponding to intraligand charge transfer (ILCT) that are sensitive to changes in solvent and pH. Strong emission in the visible region involving the ILCT state is observed in two of the complexes (Φ(e) = 0.7% and 2.6%) in acetonitrile. In the heteroleptic aniline/benzyl alcohol complex the Stokes shift is shown to be linearly related to solvent polarisability according to the Lippert equation, but only for solvents with weak hydrogen bonding interactions. Additionally, in water, emission from the ILCT state is quenched and only weak ligand centred (LC) emission is observed. The long lifetimes and quantum yields of these complexes make them interesting candidates for probes in sensing applications, especially [Ir(tpy-φ-CH(2)OH)(tpy-φ-NH(2))(2)](PF(6))(3) due to its unusual sensitivity to the solvent environment. 相似文献
46.
Adams RD Pearl WC Wong YO Zhang Q Hall MB Walensky JR 《Journal of the American Chemical Society》2011,133(33):12994-12997
The six-membered heavy atom heterocycles [Re(2)(CO)(8)(μ-SbPh(2))(μ-H)](2), 5, and Pd[Re(2)(CO)(8)(μ-SbPh(2))(μ-H)](2), 7, have been prepared by the palladium-catalyzed ring-opening cyclo-dimerization of the three-membered heterocycle Re(2)(CO)(8)(μ-SbPh(2))(μ-H), 3. The palladium atom that lies in the center of the heterocycle 7 was removed to yield 5. The palladium removal was found to be partially reversible leading to an unusual example of host-guest behavior. A related dipalladium complex Pd(2)Re(4)(CO)(16)(μ(4)-SbPh)(μ(3)-SbPh(2))(μ-Ph)(μ-H)(2), 6, was also formed in these reactions of palladium with 3. 相似文献
47.
This article presents a simple, low-cost method of fabrication and the applications of flexible polystyrene microfluidic devices with three-dimensional (3D) interconnected microporous walls based on treatment using a solvent/non-solvent mixture at room temperature. The complete fabrication process from device design concept to working device can be completed in less than an hour in a regular laboratory setting, without the need for expensive equipment. Microfluidic devices were used to demonstrate gas generation and absorption reactions by acidifying water with carbon dioxide (CO(2)) gas. By selectively treating the microporous structures with oxygen plasma, acidification of water by acetic acid (distilled white vinegar) perfusion was also demonstrated with the same device design. 相似文献
48.
Dr. Jia Wang Dr. Yong Chen Dr. Yuen‐Chi Law Meiyi Li Dr. Ming‐Xin Zhu Dr. Wei Lu Dr. Stephen Sin‐Yin Chui Dr. Nianyong Zhu Prof. Dr. Chi‐Ming Che 《化学:亚洲杂志》2011,6(11):3011-3019
A series of phosphorescent terpyridyl platinum(II) complexes with ancillary biphenylacetylide ligands, namely, [(R3tpy)PtC≡C(biphenyl)]X (R=tBu, H, or Et2N; tpy=2,2′;6′,2′′‐terpyridyl; X is an anion) were synthesized and structurally characterized by various spectroscopic techniques and X‐ray diffraction methods. Despite a lack of long alkyl chain(s) or hydrogen‐bonding motif(s), complexes [(tpy)PtC≡C(biphenyl)]Cl and [(tBu3tpy)PtC≡C(biphenyl)]X (X=Cl, ClO4, PF6, or BF4) were found to gelate water and organic solvents, respectively. The self‐aggregation of these complexes in solutions and the resulting gels were investigated with variable‐temperature (VT) 1H NMR spectroscopy, polarized optical microscopy, and absorption/emission spectroscopy. SEM micrographs on dry gels revealed entangled nanofibers with diameters of 20–40 nm and lengths of tens of micrometers. Powder X‐ray diffraction (PXRD) study revealed various degrees of crystallinity of these fibrillar nanostructures. The substituents on both the terpyridyl and acetylide ligands and counterion of these complexes play a profound but concerted role in tuning the intermolecular metal???metal and/or π–π interactions, and hence the gelation properties. 相似文献
49.
C. Poor D. S. Yuen 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2005,75(1):51-75
For a Siegel modular cusp formf of weightk letv(f) be the closure of the convex ray hull of the support of the Fourier series inside the cone of semidefinite forms. We show
the existence of the extreme core,C
ext, which satisfiesv(f) ⊇k Cext for all cusp forms. This is a generalization of the Valence Inequality to Siegel modular cusp forms. We give estimations
of the extreme core for general n. For n ≤5 we use noble forms to improve these estimates. Forn = 2 we almost specify the extreme core but fall short. We supply improved estimates for all relevant constants and show optimality
in some cases. The techniques are mainly from the geometry of numbers but we also use IGUSA’s generators for the ring of Siegel
modular forms in degree two. 相似文献
50.
Kun‐Li Wang Tseung‐Yuen Tseng Hung‐Lung Tsai Sheng‐Chieh Wu 《Journal of polymer science. Part A, Polymer chemistry》2008,46(20):6861-6871
A series of poly(aryl ether)s were successfully prepared via aromatic nucleophilic substitution reaction from various bisphenols and a novel bipolar aryl difluoride monomer containing electron‐donor triphenylamine and electron‐acceptor 1,2,4‐triazole moieties. The poly(aryl ether)s exhibited excellent solubility in organic solvents such as dimethylformamide, chloroform, and tetrahydrofuran at room temperature. The poly(aryl ether)s showed high thermal stability with Td10 higher than 500 °C and glass transition temperatures (Tg) higher than 187 °C. The thin films of the poly(aryl ether)s indicated bistable resistive switching behavior with ON/OFF current ratios as high as 103. The switching on and switching off bias voltages of the poly(aryl ether)s were affected by the bisphenol moiety. The good resistive switching behavior of the poly(aryl ether)s made them promising candidates for future nonvolatile memory applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6861–6871, 2008 相似文献