Terminal Configuration Research Articles

The alteration of blood group antigens by carbodiimide.

SummaryEthyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (CDD) inhibits the expression of many blood group antigens of the human red cell. A notable exception is the ABO system. The alteration did not seem to be reversible by ordinary methods. Sialic acid blocks the effect of CDD and may indicate the structure of the terminal chemical configuration.

Crystal and molecular structures of di-µ-bromo-dibromo-trans-bis-(dimethyl sulphide)-dipalladium(II), Pd2Br4(SMe2)2, and tetrabromo-µ-bis(diethyl sulphide)-diplatinum(II), Pt2Br4(SEt2)2

The crystal structures of Pd2Br4(SMe2)2 and Pt2Br4(SEt2)2 have been determined by single-crystal X-ray analysis. Both crystals are monoclinic, space-group P21/n which, with Z= 2, requires both molecules to posses a centre of symmetry. In fact both molecules have a planar skeleton comprising two metal atoms held apart by bridging groups, but whereas in Pd2Br4(SMe2)2 the bridging groups are halogen, with the sulphur atoms in a trans terminal configuration, in Pt2Br4(SEt2)2 the metal atoms are symmetrically bridged by the sulphur atoms, and all the halogens are terminal. These structures were determined to corroborate evidence from infrared spectral studies that, despite similar modes of preparation, these crystals possess fundamentally different structures.In Pd2Br4(SMe2)2, a= 6·00, b= 10·49, c= 11·47 A, β= 107° 35′ . The Pd–Br terminal distance is 2·404(4) significantly shorter than the (weighted mean) Pd–Br bridging distance of 2·440(10)A. The Pd–S terminal distance is 2·30(2), significantly longer than the (weighted mean) Pt–S bridging distance in Pt2Br4(SEt2)2 of 2·22(1)A. The carbon atoms of the methyl groups attached to the sulphur atoms are not symmetrically related to the plane of the molecule; one S–C bond lies close to the plane, the other nearly perpendicular to it.In Pt2Br4(SEt2)2, a= 7·36, b= 13·45, c= 9·20 A, β= 104° 05′ . The (weighted mean) Pt–Br terminal distance of 2·385(8)A is closely similar to the Pd–Br distance in Pd2Br4(SMe2)2, while the Pt–S distance is significantly shorter. The sulphur-carbon bonds are here symmetrically related to the plane of the molecule.

Houston's Jetero Airport: Location and Configuration

The master plan adopted by Houston, Texas for the new Intercontinental Airport establishes general conclusions and recommendations for the two-stage development of the airport. Eighty gates as well as parking facilities for general aircraft will eventually be required. Smooth flow of traffic as well as restaurant, mail, communications and facilities for Federal agencies, weather reporting and communications must be considered in terminal layout. The terminal apron configuration evolves naturally from the terminal configuration. Fixing definite gate spacings becomes a geometrical problem based on the number of gates and the necessary clearances. Inherent flexibility within the pier areas must exist for possible future development. Approximately half of the parking spaces are in a garage beneath the terminal building; the rest are south of the building. In addition, attendant parking is available. The lower level contains the ticket areas; the upper level contains the waiting and related areas; and the core provides overnight facilities and meeting rooms. Space is also provided for cargo, emergency equipment, fueling (a bulk storage area has been selected), and airline hangars and maintenance. A central heating and air conditioning system will be provided. Electrical facilities, water supply, sanitation, and drainage facilities are provided in the master plan.

The Flow of Liquids Through Capillaries

A simple theory of the flow of a liquid from a reservoir, through a capillary, into a second reservoir is developed, and the conclusions from it are shown to accord with the observations of Bond and of Poiseuille, and with a qualitative study of the flow by means of colored streams. It is shown that, for viscosimeters of this type, the common interpretation of that term (with coefficient $m$) in the viscosimeter equation which is frequently called the kinetic energy correction is entirely incorrect. That term is an inertia correction; it does not arise from any loss of head attendant upon the imparting of kinetic energy to the liquid, but solely from a progressive change in the distribution of the flow in the exit reservoir. It is not the correction which was considered by Hagenbach. For ideal conditions, $m$ is probably equal to unity. At very low velocities, the distribution of the flow in each reservoir is independent of the velocity, and consequently the inertia term vanishes; at this stage the Couette correction is $2e$, twice what it is when the distribution in the exit reservoir is changing. From Bond's data, it is found that $e=0.573r$. At a certain velocity, simply related to $e$, the distribution of the flow in the exit reservoir begins to change, the inertia term appears. Bond found that this occurs when the Reynolds number is 10. Under certain stated conditions, the initial distribution of flow can be retained to a much higher velocity; in these cases the inertia correction does not enter, and $\mathrm{pt}$ is independent of the velocity. There are indications that for very short tubes $\mathrm{pt}$ ceases to be linear in the velocity before the flow in the tube becomes turbulent. An explanation is offered. Changes in the terminal configurations affect both the Couette correction and the inertia correction, and the second may be markedly affected by changes in the size and form of the exit reservoir. As commonly used, the subdivided tube method for determining $e$ is entirely unreliable.