A Review of infrared spectroscopic studies of vapor-deposited dielectric glass films on silicon

Vibrational studies of a variety of thin dielectric glass films relevant to the silicon technology are reviewed. Attention is focused on those results and structural infor-mation obtained by direct transmission of materials vapor-deposited on single-crystal silicon substrates in the infra-red region 250 to 4000 cm^-1. In particular, the structure and bonding in some simple CVD binary silicate films are discussed in some detail in light of the recent vibrational analyses performed on the borosilicate and phosphosilicate systems.     

Pyrolysis studies of organic oxygenates: 3. High temperature rearrangement of aryl alkyl ethers

Thermal chemistry pathways of aryl alkyl ethers have been investigated under coal conversion-like conditions. Anisole is a thermally reactive compound having an oxygen functionality found in such coal precursors as lignins. Pyrolysis of anisoles was carried out using small batch autoclaves. Under thermolysis conditions anisole yielded a product distribution strongly dependent upon experimental parameters. Phenol, methane, CO and benzaldehyde are the low molecular weight products and polyphenyls and polyethers are the predominant high molecular weight products. The generation of CO is explained by a high temperature rearrangement of the phenyl group from O- to C- followed by rapid thermal decarbonylation of the benzaldehyde. Carbon monoxide formation from aryl alkyl ethers can thus be an important mechanistic pathway in coal conversion processes. By investigating the rearrangement using para-fluoroanisole it was shown that this rearrangement proceeds via a three-centered intermediate to para-fluorobenzaldehyde. No meta isomer was observed.     

Accumulation and depuration of tetramethyllead by rainbow trout

Tetramethyllead was found very toxic especially to juvenile rainbow trout (Salmo gairdneri). It was accumulated rapidly from the water by the fish and the highest concentration was found in the lipid layer of the intestine. Depuration of Me₄Pb from the fish organs was initially quite rapid, followed by a slower decrease and eventually reaching residual levels. Environmental concentrations of Me₄Pb detected in the fishery products thus represent a balance between uptake and depuration of this compound in fish.In conjunction with this study, a dosing system for exposing rainbow trout to Me₄Pb was developed.     

Analysis of oxygen content in steel by means of 14 MeV neutrons

A sealed-tube type 14 MeV neutron generator with maximum neutron output of 10¹¹ n/sec, incorporating a pneumatic sample transfer system of single-tube type and with a single rotation of the sample during neutron irradiation, is used to develop a method for determining oxygen content in steel in the ppm range with the best precision, and at the same time, to make the process suitable for routine work in industrial applications. The pneumatic sample transfer system is made to incline at an angle of about 20° towards the horizontal at the irradiation station. Together with a constant pressure gas reservoir for providing a constant optimum gas pressure in the transfer tube, the system gives a result of nearly perfect reproducibility in the operation.A pulse shape analyser system incorporating an organic scintillation detector is used for monitoring neutron flux level during the neutron irradiation of the sample. The percentage standard deviation of the neutron counts by the present monitoring system ranges from 0.9 to 2.7% with 0.5% as the percentage statistical deviation alone.Polyethylene, of oxygen content 163 ppm determined by comparison with lucite, is used as the steel sample carrier. A 3 × 3 in. NaI(Tl) crystal is used with a single channel analyser to count the 6.1 and 7.1 MeV gamma rays emitted from ¹⁶N as a result of the reaction ¹⁶O(n, p)¹⁶N. An optimum combination for the time of irradiation, delay and counting of the induced activity; of 30, 0.1 and 30 sec, respectively, is chosen in the present experiment. Thus, for a 100 g steel sample with an oxygen concentration of 170 ppm, the percentage standard deviation is about 4.4% which is, in fact, the counting statistic itself, resulting from a neutron flux level of 1.3 × 10⁸ n/sec cm² at the sample. As the present activation analysis makes use of the comparison method, a steel-mylar standard made of layered steel and mylar discs is prepared and a calibration curve constructed. A method of correcting the oxygen contribution in the polyethylene sample carrier is devised and the content of oxygen in the steel standard is determined.A survey of neutron flux distribution is also attempted and it is found that nearly symmetrical distribution of the flux, about the centre of the sample carrier which is placed with its axis in parallel to the plane of the disc-shaped target of the neutron-generating tube, is far from being flat.     

Time Diversity with Adaptive Error Detection to Combat Rayleigh Fading in Digital Mobile Radio

A new diversity technique is proposed to combat Rayleigh fading in digital mobile radio systems transmitting speech signals. The speech signals are μ-law PCM encoded (mu = 255, 8 kHz sampling, 8 bits/code word, 64 kbit/s data rate), and alternate data words are used to form two streams called "odd" and "even." The even stream is delayed by τ seconds and the streams are interleaved prior to radio transmission using two-level PSK modulation. At the receiver the odd data stream is delayed by τ and interleaved with the even stream. Consequently, if an error burst occurs, the effect of the reshuffling of the data stream is, in general, to place words with bit errors in juxtaposition to those correctly received. After μ-law PCM decoding of the words, a statistical error detection strategy is evoked to identify the erroneous samples. These samples are replaced by adjacent sample interpolation to give the recovered speech sequence. No recourse to channel protection coding is made. In our experiments a Rayleigh fading envelope was generated from a hardware simulator and stored in a computer, along with four sentences of speech. The system was then simulated and the recovered speech perceived. The objective performance measures were segmental SNR for the audio signal, and BER. Different error detection strategies were examined and restrictions on τ investigated. For a mobile speed of 30 mph, SNR values of 32, 21, and 16 dB were obtained for BER values of 0.1, 1, and 2 percent, corresponding to SNR gains over an uncorrected system of 3, 9, and 11 dB, respectively.     

Thermodynamic systems analysis—I. A graph-theoretic approach

An analysis of thermodynamic systems using the porcess graph model is presented in this paper. The process graph model is a linear-graph representation of systems undergoing thermodynamic processes. It provides a concise model of the interconnections and interaction interfaces of a thermodynamic system with respect to all types of flows. The analysis procedure accounts for all types of work, heat flow, and their interactions in a unified manner. The modelling and analysis procedures are illustrated by examples.The relation between the postulates of system theory and the laws of thermodynamics are stated as theorems. The first and second law analyses in thermodynamics are shown to be direct applications of network postulates from system theory. Appropriate system variables, namely, energy flow and exergy factors are introduced, which are shown to correspond to through and across variables, respectively.     

GC-MS detected difunctional carboxylic acids released by driedCladophora at the pH of lake ontario and the st. lawrence river

A study to identify the acidic components ofCladophora glomeata active againstAedes triseriatus larvae was extended to a mixture obtained by extracting the dried powdered alga in aqueous suspension at pH 8.5. The presence of 1,9-nonanedioic, 1,10-decanedioic, 1,11-undecanedioic and 4-ketononanoic acids was determined by GC-EIMS and GC-CIMS and confirmed by analytical coinjection GC. The presence of 5-pentyldihydro-2(3H)-furanone, a minor component, was also indicated. The group of major acidic constituents is different from those obtained by extracting driedCladophora with methanol. In contrast to the C₁₀–C₁₄ monocarboxylic acids, which hadLD ₅₀ values<20 ppm againstA. triseriatus, none of the dicarboxylic acids of the series G₄–C₁₄, C₁₆, and C₂₂ were active; nor were 4-ketononanoic acid and 5-pentyldihydro-2(3H)-furanone active.     

The effects of cholinergic compounds on the development of morphine tolerance, dependence and increased naloxone potency in mice

The effects of chronic treatment with morphine and cholinergic compounds on the development of morphine tolerance, physical dependence and increased naloxone potency were studied. Using the abdominal constriction method, it was shown that morphine tolerance was apparent after s.c. administration of morphine 20.0 mg/kg three times a day for four days. It was found that, in animals which showed a low degree of morphine tolerance, the naloxone potency was similar to that determined in mice which had been pretreated with only a single dose of morphine which causes no measurable tolerance. Thus, the development of increased naloxone potency and tolerance to morphine do not parallel each other. In addition, while atropine inhibited, and anti-cholinesterase drugs enhanced, the development of increased naloxone potency caused by morphine treatment they had no or little effect on the development of morphine tolerance. Furthermore, chronic treatment with cholinergic agonists reduced, while muscarinic antagonist enhanced, the development of physical dependence on morphine as assessed by withdrawal jumping and body weight loss. It is concluded that the increased potency of naloxone in antagonising the antinociceptive effect of morphine can be dissociated from the development of tolerance to, and physical dependence on, morphine in mice.