Polymeric schiff's base chelates and their precursors 8a), some cobalt chelates as catalysts for the isomerization of quadrycyclane to norbornadiene

Summary Starting with Z-2, 3-diamino-2-butenedinitrile as diamine component the synthesis of the low molecular N,N,O,O-chelate 3.Co and its ligand 3 is optimized. An easy synthesis of the chelate 8.Co covalently bound on macroreticular resins is presented. The chelates 8.Co are the most active heterogenous catalysts for the valence isomerization of quadricyclane to norbornadiene today.     

Application of the methylene blue test to cement raw materials

Characterisation of raw materials for Portland cement manufacture by use of the methylene blue adsorption method is discussed. The method is shown to be a simple, convenient ‘rule of thumb’ procedure. It provides a guide to the quantity and type of argillaceous minerals present in a given raw material sample.     

Determination of naphthalene-2,3-dicarboxaldehyde-labeled amino acids by open tubular liquid chromatography with electrochemical detection

Naphthalene-2,3-dicarboxaldehyde (NDA) has been investigated as a new derivatizing reagent for the electrochemical detection of tagged amino acids. Gradient elution allowed for the separation of 18 NDA-derivatized amino acids on an open tubular liquid chromatography column in less than 50 min. Gradient elution and electrochemical detection were found to be compatible. A detection limit of 36 amol was obtained for the asparagine-NDA derivative. The usefulness of this technique for quantitation was demonstrated by the analysis of the NDA-tagged hydrolysis products from bovine chymotrypsinogen.     

Wear in check valves due to flow induced motion

Experiments showing the frequency and amplitude of the flow induced motion of the gate for a 2- and a 4-in. swing check valve have been performed. The gate motion is due to turbulence in approach flow. We have found the dominant turbulent frequency of the approach flow is about half the natural frequency of the valves. The valves appear to be almost critically damped. Because of this, the valves respond almost as they would to a static force of the magnitude characteristic of the turbulent fluctuation in the flow. Both the dimensionless exciting force and the damping ratio have been found to be independent of valve size so the above statements are true for larger valves also. The recommended valve oscillation amplitudes and frequencies are used to calculate the wear at the shaft and at the stop. For an unpegged check valve, such as one of the 10-in. valves which was used at the San Onofre Nuclear Generation Station, it was found that shaft bearing wear would amount to 0.27 in.³/year and stop wear to 0.03 in.³/year.     

ISDN: A Global Solution to Transmission Needs

The concept of the integrated services digital network (ISDN) could revolutionize information management. The purpose of the ISDN is to provide a worldwide network that offers end-to-end digital connectivity supporting a wide variety of communications services. ISDN subscribers will have direct access to a high-speed digital pipeline capable of supporting simultaneous voice, data, facsimile, and various other services and calling features.     

Driver detection and recognition of lineside signals and signs at different approach speeds

A study was carried out using simulation to investigate driver responses to lineside signals and signs at various approach speeds. The objectives of the study were: (1) to find out whether train speed would significantly affect signal/sign reading; (2) to examine at which point certain types of signs or signals could be detected or recognised, and (3) to determine a speed cut-off level above which certain types of signs or signals are no longer recognisable or detectable. Fifty-seven train drivers from 12 Train Operating Companies in the UK participated in the trials. Twenty different types of lineside signs and ten types of signals were tested under six different approach speeds ranging from 100 to 350 km/h (62–218 mph). Driver performance measures were ‘time remaining to the signal/sign’ at the point of detection or recognition, and reading error rate. The results showed a significant influence of train speed on driver responses to lineside signals/signs and demonstrated a non-linear relationship between driver responses to signals/signs and approach speed. This has been used to estimate a maximum approach speed limit within which a specific signal or sign can be correctly detected or recognised. The findings and implications of the study are discussed in the paper.     

Reliability prediction models to support conceptual design

During the early stages of conceptual design, the ability to predict reliability is very limited. Without a prototype to test in a lab environment or without field data, component failure rates and system reliability performance are usually unknown. A popular method for early reliability prediction is to develop a computer model for the system. However, most of these models are extremely specific to an individual system or industry. This paper presents three general procedures (using both simulation and analytic solution techniques) for predicting system reliability and average mission cost. The procedures consider both known and unknown failure rates and component-level and subsystem-level analyzes. The estimates are based on the number of series subsystems and redundant (active or stand-by) components for each subsystem. The result is a set of approaches that engineers can use to predict system reliability early in the system-design process. Software was developed (and is discussed in this paper) that facilitates the application of the simulation-based techniques. For the specific type of system and mission addressed in this paper, the analytic approach is superior to the simulation-based prediction models. However, all three approaches are presented for two reasons: (1) to convey the development process involved with building these prediction tools; and (2) the simulation-based approaches are of greater value as the research is extended to consider more complex systems and scenarios     

High-Frequency Variations in the Rotation of the Earth

We report here observational results demonstrating that a three-station network of properly distributed VLBI observatories can routinely determine UT1 with a formal standard error of ±0.05 ms of time, in an observing period of 24 h. We also report the results of a three-month series of daily observing sessions of only 1-h duration with a single interferometer, which produced estimates of UT1 with standard errors of ±0.1 ms. The UT1 values obtained from the 1-h observing sessions track smoothly between the points of the 24-h time series, and the combined time series shows that it is not unusual for UT1 to vary by 1-2 ms in periods of several days. Preliminary results of reprocessing the 24-h observing sessions in 2-h segments suggest that variations of 0.4 ms may occur on time scales of only 6-8 h.     

Microprocessor-Based Control of an Ion Beam Deposition System

A microprocessor-based system with 32 A/D, 24 D/A, and 16 ac load controllers, has been designed and built to monitor and control an ion beam thin-film deposition system. The A/D and D/A channels have electrical isolation of 7.5 kV between channels and between input and output. The microprocessor system keeps the ion beam deposition parameters stable for extended periods of operation and it is proposed as a means to greatly simplify switching from one deposition species to another to grow thin multilayer or alloy films.     

Intramolecular crosslinking of poly(vinyl alcohol)

Poly(vinyl alcohol) is crosslinked in dilute solution (c=0.1 wt%) with glutaraldehyde. The reaction product is characterized by viscometry and gel permeation chromatography (g.p.c.). The intrinsic viscosity decreases with increasing degree of crosslinking and does not depend on temperature. G.p.c. reveals that the reaction product is not homogeneous, but consists of a mixture of particles with different sizes, possibly both intra- and intermolecularly crosslinked molecules. The intramolecularly crosslinked molecules are smaller in size than the initial polymer molecules and their size depends on the degree of crosslinking. They possess a narrow particle size distribution even if the initial polymer sample had a broad molecular weight distribution.