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91.
Hong-Gyu Park Young Soo Park Kyoung Yong Park Min Sun Kim Hae-Chang Jeong 《Liquid crystals》2013,40(9):1262-1268
We demonstrate homogeneous and uniform liquid crystal (LC) alignment on poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] films using ion-beam (IB) irradiation and a performance improvement of twisted nematic (TN) cells using IB-irradiated PVDF-TrFE films. Spontaneous ferroelectricity of the PVDF-TrFE films was modified by IB irradiation, which affected the LC alignment properties. The variation in the pre-tilt angles of the LC molecules on the IB-irradiated PVDF films is attributed to surface reformation, including defluorination and oxidation because the pre-tilt angles of LC molecules can be controlled by adjusting the fluorine content. The results of contact angle measurements supported this phenomenon. A 58% reduction in the switching voltage was observed for TN cells, indicating that the IB-irradiated PVDF-TrFE films are a promising candidate for use as an alignment layer. 相似文献
92.
Mir M. Alavi Nikje Mohammad A. Bigdeli 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1445-1448
The solventless oxidation of benzaldehydes to carboxylic acids using oxone/wet-alumina under microwave irradiations is described. 相似文献
93.
V. I. Shulga 《辐射效应与固体损伤》2013,168(1-4):65-83
Sputtering of Cu single-crystal and polycrystal targets by 27 keV Ar ions has been simulated using the new binary collision cascade computer program OKSANA. The sputtering yield, the sputtering and reflection efficiencies, and the absolute and relative contributions to sputtering from various components have been calculated in a broad range of incidence angles. The obtained angular dependences of the sputtering yield have proved to agree with experimental data. Some features of sputtering due to semichannel focusing of incident particles have been found. The contributions to sputtering from several types of linear collision chains and from the primary knock-on atoms are considered in most detail. It has been shown, in particular, that the pure focused, pure defocused, and mixed focused-defocused collision chains contribute noticeably to sputtering. The contribution from the primary knock-on atoms is angle-dependent and reaches its maximum in the range of glancing angles for both single-crystal and polycrystal targets. 相似文献
94.
Abstract Cascade size may affect phase stability under irradiation because of two distinct contributions: the replacement to displacement cross-section ratio depends on the deposited energy density; ballistic jumps which tend to disorder ordered compounds occur by bursts, while thermal jumps which restore long range order occur one by one. The latter effect cannot be handled by standard rate theory. A stochastic treatment of the problem, based on a Fokker Planck approximation of the relevant master equation is summarized. It is shown that the possible values of the long range order parameter under irradiation are not affected by the size of the cascade but that the respective stability of the former is cascade size sensitive. As a consequence, the stability diagram of phases under irradiation varies with the size of the cascades. A numerical example of this is given for the B2 structure. 相似文献
95.
P. K. Kamweru F. G. Ndiritu T. K. Kinyanjui Z. W. Muthui R. G. Ngumbu P. M. Odhiambo 《Journal of Macromolecular Science: Physics》2013,52(7):1338-1349
Plastic bags mostly made of polyethylene (PE) cause pollution as solid waste due to their non-degradability nature. Initiation of a degradative process by enhanced photo-oxidation is a possible method for an accelerated degradation. This paper presents temperature treatment effects on PE films where photodegradation was initiated using ultraviolet (UV) irradiation in the ranges of 200–300 nm and 300–400 nm for 2 hr. Effects of temperature of 40°C and 55°C on non-UV-irradiated and UV-irradiated PE films processed by conventional methods were investigated and evaluated after 50 hr, 150 hr, and 350 hr of temperature exposure. The effects of UV wavelength range irradiation on the degradation were deduced. Measuring the dynamic moduli using a dynamic mechanical analyzer monitored the degradation. The decrease in average storage modulus was 62% with treatment at 55°C, higher than the 16% drop at 40°C for unirradiated samples after 350-hr exposure. Cross-linking in UV-exposed samples, characterized by an increase in dynamic modulus (stiffening), was observed followed by a reduction of storage modulus. Temperature treatment at 55°C together with 300–400-nm UV range irradiation resulted in the largest increase, i.e., 22% after 150 hr, followed by the largest reduction of storage modulus, i.e., 74.6% for a cumulative 350-hr exposure. 相似文献
96.
The carbon-13 chemical shifts of seven N-(4-substituted phenyl) piperidine; the corresponding N-oxides, and their thermal rearrangement products were analyzed and assigned. The N-oxidation effect on the carbon-13 chemical shift is discussed, a correlation of N-oxidation effect with substituent constant (σp, σm, σI and σR) has been studied; dual substituent-parameter equation produce better correlation. 相似文献
97.
An optical study of the D-D neutron irradiation-induced defects in Co-and Cu-doped ZnO wafers 下载免费PDF全文
Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped(1×1014,5×1016,and 1×1017cm-2) and Cu-doped(5×1016cm-2) ZnO wafers irradiated by D-D neutrons(fluence of 2.9×1010 cm-2) have been investigated.After irradiation,the Co or Cu metal and oxide clusters in doped ZnO wafers are dissolved,and the wu¨rtzite structure of ZnO substrate for each sample remains unchanged and keeps in high c-axis preferential orientation.The degree of irradiation-induced crystal disorder reflected from the absorption band tail parameter(E0) is far greater for doped ZnO than the undoped one.Under the same doping concentration,the Cu-doped ZnO wafer has much higher irradiation-induced disorder than the Co-doped one.Photoluminescence measurements indicate that the introduction rate of both the zinc vacancy and the zinc interstitial is much higher for the doped ZnO wafer with a high doping level than the undoped one.In addition,both crystal lattice distortion and defect complexes are suggested to be formed in doped ZnO wafers.Consequently,the Co-or Cu-doped ZnO wafer(especially with a high doping level) exhibits very low radiation hardness compared with the undoped one,and the Cu-doped ZnO wafer is much less radiation-hard than the Co-doped one. 相似文献
98.
Hemant P. Narkhede Uttam B. More Dipak S. Dalal Nilesh S. Pawar Dhananjay H. More 《合成通讯》2013,43(4):573-577
Microwave‐assisted, solvent‐free alkylation and acylation of 2‐mercaptobenzothiazole has been attempted using silica gel, alumina, and a new solid support, fly ash. Fly ash, a waste generated at thermal power stations, could be used as solid support just as efficiently as commercial supports. The additional features of methodology include a much faster reaction, easy workup, higher yields, higher purity of the products, and an ecofriendly approach. 相似文献
99.
Molecular dynamics simulations of the displacement cascades in Fe-10%Cr systems are used to simulate the primary knocked-on atom events of the irradiation damage at temperatures 300,600,and 750 K with primary knockedon atom energies between 1 and 15 keV.The results indicate that the vacancies produced by the cascade are all in the central region of the displacement cascade.During the cascade,all recoil Fe and Cr atoms combine with each other to form Fe-Cr or Fe-Fe interstitial dumbbells as well as interstitial clusters.The number and the size of interstitial clusters increase with the energy of the primary knocked-on atom and the temperature.A few large clusters consist of a large number of Fe interstitials with a few Cr atoms,the rest are Fe-Cr clusters with small and medium sizes.The interstitial dumbbells of Fe-Fe and Fe-Cr are in the 111 and 110 series directions,respectively. 相似文献
100.
A new environmentally benign, convenient, and facile methodology for the N-formylation of amines is reported using ultrasound irradiation under solvent- and catalyst-free conditions at room temperature. Compared with conventional methods, the main advantages of the present procedure are milder, cleaner and greener conditions, shorter reaction time, higher purity and yields, simpler work-up, and lower generation of waste or pollutions. 相似文献