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51.
An in situ deposition approach was used for the synthesis of nano‐CaSO4 and nano‐Ca3(PO4)2. The nanosize particles were confirmed with an X‐ray diffraction technique. Composites of polypropylene (PP) with 0.1–0.5 wt % nano‐ or commercial CaSO4 or nano‐Ca3(PO4)2 were prepared. The transition from the α phase to the β phase was observed for 0.1–0.3 wt % nano‐CaSO4/PP and nano‐Ca3(PO4)2/PP composites. This was confirmed by Fourier transform infrared. A differential scanning calorimetry analysis was carried out to determine the thermal behavior of the nanocomposites with increasing amounts of the nano‐CaSO4 and nano‐Ca3(PO4)2 fillers. Increases in the tensile strength and Young's modulus were observed up to certain loading and were followed by a decrease in the tensile strength. A continuous decrease in the elongation at break (%) was also observed for commercial CaSO4 and larger nano‐Ca3(PO4)2. A decrease in the mechanical properties after a certain loading might have been due to the agglomeration and phase transition of PP in the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 670–680, 2007 相似文献
52.
Martin P. Harmer Raja K. Mishra Gareth Thomas 《Journal of the American Ceramic Society》1983,66(3):44-C-
( Ni,Zn)Fe2 O4 samples containing small amounts of Co were characterized in a transmission electron microscope to ascertain the micro structural changes accompanying low-temperature oxidation of the samples. Although no new features resulting from oxidation were observed, prominent surjace reduction occurred in the thin foil specimens. Formation and growth of Ni particles on the ferrite surface are explained using the heats of formation of the oxides.2 相似文献
53.
D. Parida P. Nayak D. K. Mishra S. Lenka P. L. Nayak S. Mohanty K. K. Rao 《应用聚合物科学杂志》1995,56(13):1731-1738
Castor oil was reacted with isophorone diisocyanate varying the isocyanate/hydroxyl ratio to produce a number of polyurethanes (PUs). All the PUs were reacted with acrylamide and methacrylamide using ethylene glycol dimethacrylate as the crosslinker and benzoyl peroxide as the initiator. Thermogravimetric analysis of the polymers was conducted using a computer analysis method for assigning the kinetic mechanism. The degradation steps have been discussed in the light of the kinetic parameters. © 1995 John Wiley & Sons, Inc. 相似文献
54.
The feasibility of chromium(VI) to induce graft copolymerization of methyl methacrylate onto nylon-6 was investigated in the presence of nitrogen. The rate of grafting was determined by varying monomer concentration, chromium(VI) concentration, temperature, acidity of the medium, solvents, inorganic salts, and redox system. The graft yield increases significantly by increasing the monomer concentration. The graft yield increases with increase of [Cr(VI)] up to 0.025 mole/liter. With further increase of [Cr(VI)], the graft yield decreases. The increase of acid concentration up to 0.395 mole/liter results the increase in graft yield. Beyond this concentration the graft yield decreases. The graft yield increases with increase in temperature up to 55°C and thereafter it decreases. The graft yield is medium dependent. The graft yield increases with increasing thiourea concentration upto 0.0025 mole/liter but beyond this concentration, the percentage graft yield decreases. A suitable kinetic scheme has been proposed and the rate equation has been evaluated. 相似文献
55.
Chemical analysis of volatiles emitted by Pinus svlvestris after induction by insect oviposition 总被引:1,自引:0,他引:1
Gas chromatography – mass spectrometry analyses of the headspace volatiles of Scots pine (Pinus sylvestris) induced by egg deposition of the sawfly Diprion pini were conducted. The odor blend of systemically oviposition-induced pine twigs, attractive for the eulophid egg parasitoid Chrysonotomyia ruforum, was compared to volatiles released by damaged pine twigs (control) that are not attractive for the parasitoid. The mechanical damage inflicted to the control twigs mimicked the damage by a sawfly female prior to egg deposition. The odor blend released by oviposition-induced pine twigs consisted of numerous mono- and sesquiterpenes, which all were also present in the headspace of the artificially damaged control twigs. A quantitative comparison of the volatiles from oviposition-induced twigs and controls revealed that only the amounts of (E)--farnesene were significantly higher in the volatile blend of the oviposition-induced twigs. Volatiles from pine twigs treated with jasmonic acid (JA) also attract the egg parasitoid. No qualitative differences were detected when comparing the composition of the headspace of JA-treated pine twigs with the volatile blend of untreated control twigs. JA-treated pine twigs released significantly higher amounts of (E)--farnesene. However, the JA treatment induced a significant increase of the amount of further terpenoid components. The release of terpenoids by pine after wounding, egg deposition, and JA treatment is discussed with special respect to (E)--farnesene. 相似文献
56.
Dynamic, in situ wide angle X-ray scattering (WAXS) studies of the melt crystallization of injection-molded poly(ether ether ketone) (PEEK) have been carried out using an X-ray diffractometer and a position-sensitive detector. A test cell has been fabricated to fit inside the diffractometer and yet work as a complete injection molding apparatus. The rate of crystallization has been shown to increase with decreasing crystallization temperature and/or increasing flow rate in the mold. The crystallization rate decreases dramatically with increase in melt soak time at 400°C. The crystallinity index, which affects the stiffness, toughness, and fracture behavior of PEEK, has been measured under various processing conditions, by wide angle X-ray scattering, so as to optimize the process parameters: molding time, mold temperature, melt temperature, soak time at melt temperature, and flow rate. It has been shown that the crystallinity and hence the elastic modulus increase with increase in crystallization temperature and/or flow rate. Chain orientation has been shown to be absent in the bulk of the injection-molded specimens under normal molding conditions. 相似文献
57.
In this study, agrochemical was produced from waste polyesters. Reactions of waste polyesters [poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT)] powder with ethylene glycol (EG) in the presence of tetrahydrofurane (THF) using 0.003 mol lead acetate as a catalyst were carried out in a batch reactor at 470 K and at atmospheric pressure conditions. Reactions were undertaken with various particle size ranges from 50 to 512.5 μm, and reaction time from 30 to 70 min for reactions of polyesters. Low molecular weight product of polyester was obtained during this process. In the next stage, hydroxylamine hydrochloride (HAHC), cyclohexylamine (CHA), and potasium hydroxide (KOH) solution were introduced to convert low molecular weight product of polyester into terephthalohydroxamic acid (TPHA) by introduction of HCl (Hydrochloric Acid) as per stoichiometric requirement. TPHA can be used as an agrochemical (insecticide) with appreciable efficiency. To increase the polyester conversion rate, external catalyst (0.003 mol lead acetate) was introduced during the reaction. The product was deposited on the surface of unreacted polyester, which was removed from the surface by introducing dimethyl sulfoxide (DMSO). To accelerate the reaction rate, DMSO, CHA, and THF were introduced during the reaction, which has an industrial significance. Depolymerization of polyester was proportional to the reaction time. Depolymerization of polyester was inversely proportional to the particle size of polyester. Analyses of value‐added product (TPHA) and byproducts [EG and BD (1,4‐butanediol)] as well as polyesters were undertaken. A kinetic model is developed, and experimental data simulated with it, which was consistent with the model. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2504–2510, 2006 相似文献
58.
Atle Wibe Anna-Karin Borg-Karlson Monika Persson Torbjörn Norin Hanna Mustaparta 《Journal of chemical ecology》1998,24(2):273-287
The enantiomeric composition of seven monoterpene hydrocarbons in headspace volatiles of spruce sawdust and seedlings (Picea abies), pine seedlings (Pinus sylvestris), and branches of juniper (Juniperus communis) was determined by gas chromatographic separation on a -Cyclodextrin column. For the six monoterpenes, -pinene, camphene, -pinene, sabinene, limonene, and -phellandrene, both enantiomers were present, whereas for 3-carene only the (+)-configuration was found. The amount of each enantiomer varied considerably both in relation to total amount of all of them, and for the six pairs also in relation to the opposite enantiomer. One olfactory receptor neuron in the pine weevil (Hylobius abietis) showed a strong response to -pinene when stimulated with all four headspace materials via a GC equipped with a DB-WAX column. The same neuron was subsequently tested with repeated stimulations via the GC effluent containing the (+)- or (–)-enantiomer. A marked better response to (+)- than to (–)--pinene was elicited. Another olfactory receptor neuron that responded strongly to limonene when stimulated with the spruce volatiles was tested for enantiomers of limonene. This neuron responded more strongly to (–)- than to (+)-limonene, when stimulated alternately with each of the limonene enantiomers. Discrimination between enantiomers by plant olfactory receptor neurons suggests that the enantiomeric ratios of volatile compounds may be important in host location by the pine weevil. 相似文献
59.
Dheerendra Mishra 《Multimedia Tools and Applications》2016,75(23):16017-16038
The Session Initiation Protocol (SIP) is a signaling communications protocol, which has been chosen for controlling multimedia communication in 3G mobile networks. In recent years, password-based authenticated key exchange protocols are designed to provide strong authentication for SIP. In this paper, we address this problem in two-party setting where the user and server try to authenticate each other, and establish a session key using a shared password. We aim to propose a secure and anonymous authenticated key exchange protocol, which can achieve security and privacy goal without increasing computation and communication overhead. Through the analysis, we show that the proposed protocol is secure, and has computational and computational overheads comparable to related authentication protocols for SIP using elliptic curve cryptography. The proposed protocol is also provably secure in the random oracle model. 相似文献
60.
Mishra JS Sakamoto R Motojima G Matsuyama A Yamada H 《The Review of scientific instruments》2011,82(2):023505
A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100-450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii R(c) = 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes. 相似文献