Molecular packing in alkylated and chlorinated poly-p-xylylenes

The changes in the structure of poly-p-xylylene (PPX) films when substituted with chlorine (Cl), ethyl (Et), and isopropyl (iP) groups were investigated by X-ray diffraction methods. As-polymerized films exist in the α crystalline form. The reflections from these films could be indexed with a monoclinic unit cell. The cell dimensions in the plane of these films do not change with the substituents: $\text{a = 5.9}\text{A}\text{?}$, the chain axis $\text{c = 6.55}\text{A}\text{?}$, and β = 135°. However, the cell dimension b, normal to the plane of the film, varies with the groups attached to the benzene ring: PPX, 10.64 Å; PPX-Cl, 12.8 Å; PPX-Et, 13.4 Å: and PPX-iP, 14.1 Å. The molecular packing in these polymers is discussed.     

Error Margin Estimating in Repeaters

In this paper a new method of estimating error margin inTcarrier repeaters is proposed. This estimate is based on two sets of data: (a) measurements from a commonly used test wherein bipolar violations are inserted into the line at an audio rate, and (b) the crosstalk environment in which the repeater is operating. An audio component due to violations in the bipolar signal causes a shift in the eye pattern resulting in a change of repeater error rate. This in turn changes the regenerated audio signal power by an amount depending on the initial undisturbed error rate of the repeater. This then gives a basis for extrapolating the operating error rate of a repeater from a test measurement. This error rate combined with a knowledge of the cable crosstalk parameters and number of operating systems during the test, is then used to estimate the error margin or eye opening of the repeater, assuming a Gaussian distribution for the interference. A method of ranking repeaters in a repeatered line to indicate their relative margin is proposed wherein the effect of errors on the audio signal to an intermediate test repeater is taken into account. Results presented are quite general and valid at any line rate and repeater spacing, and hence applicable for differentT-carriers such asT1, T1C, T2, etc.     

Indicators of acid-base equilibrium of blood in full-term, premature and over-mature fetuses and newborn infants in different types of uterine inertia]

A detailed appraisal of the British seafarer and his way of life is described and the prevailing management of sexually transmitted disease in the seafarer is outlined. It is shown that the available statistics on the incidence of sexually transmitted disease among seafarers are inadequate. Management at sea and ashore remains generally unsatisfactory. Suggestions are made to improve the management of venereal disease in foreign ports and a simple method is described of managing sexually transmitted disease at sea with trimethoprim/sulphamethoxazole.     

Generation of permanent, dry, electrical contacts by tattooing carbon into skin tissue

The introduction of sterile collodial carbon into the dermis produces an area of low electrical resistance in the intact skin. The low resistance spot is suitable for long term, dry contact, stimulation or specialized ECG/EEG measurements.     

Use of hydrogen in dual-fuel engines

The dual-fuel method is the easiest and most flexible method for using hydrogen in a diesel engine. In this work, a conventional single cylinder, four-stroke diesel engine has been converted to work on the dual-fuel principle with hydrogen as the inducted fuel. The main objectives of the investigation were to determine the optimum proportions between hydrogen and diesel oil under various engine operating conditions and to study the combustion process in the engine under these conditions. The results show that very satisfactory dual-fuel operation with hydrogen is possible. The thermal efficiencies obtained were comparable with pure diesel operation and up to about half the engine's energy requirement could be derived from hydrogen. The chief problem noticed is that of knocking setting in well before the stoichiometric hydrogen-air ratio. This requires further research for rectification.