Materials Literature
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A series of cyclic tri- and tetra-metric phosphazenes [NP(OR)2]n(n= 3 or 4), N3P3(OR)Cl5 and N3P3(OR)4Cl2 has been prepared with 1- or 2-naphthyloxy, 1-naphthylmethyloxy, 1-naphthylethyloxy, 9-anthryloxy and 9-phenanthryloxy side groups OR. These syntheses are model processes for the preparation of the corresponding p…
Inhibiting action of semicarbazide, thiosemicarbazide, sym. diphenylcarbazide towards corrosion of zinc in hydrochloric acid has been investigated. The rate of corrosion depends on the nature of the inhibitor and its concentration. The values of inhibition efficiency from, weight loss, thermometric measurements are in…
&&Q& The aim of this paper is to provide an overview of important developments in the chemistry and the use of persistent free bi-and polyradicals to study chemical and biological model systems by electron paramagnetic resonance (epr) or as materials for physical purposes.The paper also discusses the different ways us…
Molecular orientations and surface morphology of mechanically rubbed polyimide films have been extensively studied by FT-IR, ellipsometry and atomic force microscope. In-plane and out-of-plane molecular orientations of rubbed polyimide films have been examined by angular dependences of polarized infrared transmission…
High quality graphite films have been prepared from carbonized aromatic polyimide films by short time heat treatment at 3100 and 3200°C without any pressurization. The starting materials were Kapton and Novax with 25μm thick and a high-modulus polyimide film (PPT), prepared via polyamic acid gel, with 45μ thick. Micro…
Pulse correlation in PD signals was analyzed with auto-correlation function of PD pulses occurring in tree channels at 50 Hz ac voltage application as well as PD pulses occurring in several simple model electrodes. It was clarified that the auto-correlation function of PD pulse trains was strongly affected by void sha…
The design, analysis, manufacture, and hydrostatic testing results of a 24- inchdiameter ringstiffened pressurehull model are presented. The AS-4 graphite/PEEK cylinder is manufactured using a nonautoclave insitu filament winding and tape laydown process. The cylinder incorporates 5 hoopwound rings and a shell (hoop/a…
Hybrid aligned nematic films placed onto an isotropic fluid substrate exhibit an unusual periodic stripe domain structure that appears only when the thickness of the film is smaller than a few tenths of a micrometer. We investigated the effect of a magnetic field on the threshold between the periodic stripe domains an…
Films of barium hexaferrite have been prepared by pulsed laser deposition. A systematic study of the effect of various substrates and growth conditions such as substrate temperature and oxygen deposition pressure has been performed. Results show that the crystal structure and magnetic properties of BaFe/sub 12/O/sub 1…
The fiber/matrix interfacial shear strength of Textron SCS‐6 SiC‐fiber‐reinforced reaction‐bonded Si 3 N 4 (RBSN) was studied as a function of temperature after oxidation for 24 h at 600°C. Fiber push‐out experiments were conducted using a diamond indenter in a high‐temperature micro‐hardness tester under vacuum. The…
A triplex-forming oligopyrimidine has been attached at its 5'-end to a photoreactive psoralen derivative and used to target a sequence which forms part of the coding region of the human aromatase gene. The 20 base pair sequence is not a perfect triplex target since it contains three pyrimidine interruptions within the…
Two new anionic antimony sulfide clusters [Sb6S6]2– and [Sb4S6]2– have been prepared and structurally characterized from the reduction of Sb2S5 with BH4– and [FeH(CO)4]– respectively.
A new method is described that employs dual staining and epifluorescence microscopy for the identification of plankton and detritus in seawater. The staining technique uses the fluorochromes propidium iodide (PI) and 4′.6-diamidino-2-phenylindole (DAPI) in conjunction with UV excitation. PI/DAPI staining identifies li…
A kinetic study of the transformation of cerium(III) hydroxycarbonate into ceria has been achieved by means of isothermal thermogravimetry experiments under a controlled atmosphere. A geometrical modelling based on Mampel's model allowed determination of the values and the variations of the specific rates of nucleatio…
Surface treatments by nonionic surfactant (Brij) coating and air-plasma glow discharge treatment onto polysulfone have been investigated to improve its surface properties. Surface treated samples were characterized by measurement of contact angle by a goniometer, Fourier transform infrared spectroscopy in the attenuat…
Atmospheric corrosion is relatively complex involving interactions between a metallic substrate and a dynamic atmosphere. Modelling of other corrosion processes has been carried out with some success however, little advance has been made on the modelling of atmospheric corrosion. Successful models must incorporate a d…
Inverse relaxation is a newly observed phenomenon in the domain of polymeric substances and has received scant attention. A brief account of the nature of this phenomenon is presented. The present paper is a sequel to the paper entitled ‘Analysis of Relaxation Phenomena Part I; Stress Relaxation’. Here, equations are…
When a Vicalloy wire (40wt%Fe-50Co-10V) is twisted, the coercivity reduces due to large stress. The pulse-inducing characteristics and domain wall propagation are investigated utilizing this effect on such compound magnetic wire. We find that the generating point of inverse nucleation varies according to the strength…
Electrochemical lithium insertion into W18O49 has allowed the determination of the existence of a range of intercalated phases, LixW18O49. For x < 22 the phases form through an intercalation reaction and four single-phase regions are detected: x= 0–2.6, 3.4–10, 11–15, 15.5–22. In the last of these composition ranges a…
Homologues series of some derivatives of 3,5-(4-substituted phenyl)-1,2,4-oxydiazole were synthesized and their phase behavior studied. Introduction of the pentagonal heteroaromatic ring leads to significant changes in mesomorphic behavior in comparison with analogous compounds containing the phenyl ring. The synthesi…