Surface analytical study of the interaction between γ-amino propyl triethoxysilane and E-glass surface

Time-of-flight secondary ion mass spectrometry has been used to study the interaction of -amino propyl triethoxysilane with an E-glass surface. The fragmentation pattern has been interpreted by assigning a series of mass peaks to the structural unit of the poly(aminosiloxane). The composition of the coating is complicated by the presence of polydimethylsiloxane and its copolymers. The highest mass fragment was obtained from the coating exposed by extraction with warm water (697 AMU). The largest molecular fragments would appear to have degrees of polymerization of 6 with differing numbers of silanol groups. On re-extraction with hot water the fragment size decreased. It is postulated that the network chain length of the three-dimensional polymer decreased as the interface was approached. At the glass surface a chemically bound molecular layer could be identified. The full chemical nature of the deposit is complicated by the incorporation of aluminium from the substrate into the coating. It was also possible to confirm that a layer of warm-water soluble oligomers existed at the air interface.     

Investigation of the levels of N(τ)-Methylhistidine in a range of beef cuts and offals

Protein-bound N(τ)-methylhistidine (N-MeHis) has been suggested as an index for the estimation of muscle (meat) protein in meat and meat products. This paper examines the levels of N-MeHis in a range of six prime beef cuts together with beef flank, cheek, mechanically recovered meat (MRM) and offals. The study was undertaken by two separate laboratories using a previously reported HPLC procedure involving the conversion of N-MeHis to a fluorescent derivative. It is shown that, whilst similar N-MeHis levels are present in the prime cuts, there is considerable variation in those found in the other cuts and offals. The average N-MeHis level in six prime cuts observed at both laboratories is 122 μg/g fat-free connective tissue-free (FFCF) meat; however, flank exhibits apparently high N-MeHis levels, whilst cheek and MRM contain only approximately 70% of the level found in the prime cuts. The offals contain between 0 and 65% of the N-MeHis level found in prime cuts. The greater variability and the often lower value of the N-MeHis content of these legitimate meat materials preclude the establishment of a single realistic index for FFCF beef, and present fundamental problems for the assessment of the lean meat content of manufactured beef products by N-MeHis determination.     

An integrated size and roundness adaptive control system for the plunge grinding process

A time variant, roundness based adaptive size and roundness control system is presented for the plunge grinding process which avoids the need for a large data processing capacity and compares favourably in performance with the large and expensive control system previously developed and therefore improves the prospect of industrial use. The non-linear control functions and adaptive model are presented and analysed. The hardware of the integrated, low cost system and the software algorithms used to reduce the computational power requirements are discussed and the results of grinding experiments are presented.     

An Active Feedback System for Stabilizing Visual Images

In normal vision, eye movements cause the image to move on the retina. Special apparatus can stabilize the image on the retina so it cannot move, and vision fades away. Previous methods for stabilizing the image were either optical systems or complex computer-controlled feedback systems. A simpler feedback system is presented which detects eye motion and rotates a mirror through which the target is viewed, to exactly compensate for eye motion. Unlike previous optical systems, this new system has no lenses in either the viewing or the image-forming path to limit the spatial resolution.     

On the selection of a subgoal and the use of a priori information in learning control systems

Numerous methods have been proposed for the design of control systems which learn to function in unknown or partially known environments. Most learning schemes are radical departures from the techniques using continuous adjustment of parameters which grew out of early developments in model reference systems. Principal contributions to the area have been controller models and algorithms. In studying these models, the system is abstracted to such an extent that there is quite often a loss of contact with practical considerations. The objective of this paper is to present some results in the theory of learning control, but also to look again at some of the practical problems encountered in applying a learning controller to a problem.

This paper defines the subgoal as a subordinate to the primary goal of minimizing the performance index. It must evaluate each decision one control interval after it is instituted. The subgoal problem is to choose a subgoal which will direct the learning process to the optimal as prescribed by the given performance index. An analytical solution is presented and extended heuristically for the general case. This extended method makes use of the a priori information about the plant.

Two other problems are also discussed. A fixed grid is used to partition the state space into control situations, and a method of extending the grid is proposed and evaluated. The controller is initialized using the a priori information, too. A full scale simulation confirms that the proposed methods of choosing the subgoal, extending the fixed grid and initializing the controller are improvements over previous methods.     

Mössbauer studies of iron-bearing minerals in coal and coal ash

⁵⁷Fe Mössbauer spectroscopy has been used to characterize the iron-bearing minerals present in some British Columbia coals. The minerals observed in a range of samples include pyrite/marcasite, siderite, jarosite, rozenite or melanterite, and Fe²⁺ -bearing clay minerals such as illite. The presence of jarosite is confirmed through the magnetic hyperfine interaction observed at 4.2 K. The absence of magnetic ordering at 4.2 K for the ferrous sulphate component indicates the presence of rozenite, FeS0₄ · 4H₂0, or melanterite, FeS0₄ · 7H₂0, rather than szomolnokite, FeS0₄ · H₂0 or FeS0₄. The effects of ashing on two of the coals is also studied.     

INVESTIGATION OF THE USE OF LASER-DOPPLER VELOCIMETRY IN TWO-PHASE BUBBLY FLOWS

Understanding the dynamic phenomena of viability loss of shear sensitive cells and bubble breakage and coalescence within airlift reactors requires knowledge of local, liquid-phase hydrodynamics. The laser-Doppler velocimeter (LDV) is a non-invasive instrument which may be used to obtain this information. Experimental procedures and software were developed to detect and measure Doppler bursts in two-phase flow in a split-cylinder airlift reactor. Off-line analysis of the data indicated a detection rate approximately one order of magnitude greater than that observed using an available commercial frequency tracker. Approximately 400 to 500 observations are needed for the ensemble mean to characterize the local mean velocity to within ±5% for a superficial gas velocity of 10.4 cm/s, the highest superficial gas velocity used in these studies. The limitations, prospects, and signal-processing options for LDV in this application are also discussed     

Analysis of solvent extracts of bituminous coal macerals by chromatography, 1H n.m.r. and field-desorption mass spectrometry

Analysis of the carbon disulphide extracts of nine samples of UK coal-maceral concentrates by ¹H highresolution n.m.r. spectroscopy, gas-liquid chromatography and field-desorption mass spectrometry indicates the presence of components with a wide molecular weight range extending up to 1200 amu; these are attributed to n-alkanes up to ≈C₅₀ and highly condensed polynuclear aromatic compounds.     

Influence of Carbon on SOx Emissions from Glass Processing

Carbon reacts with Na₂SO₄ in glass batches, influencing SO _x emissions. To study the role of carbon active surface area (ASA) in the decomposition phenomena, Na₂SO₄ is reacted with three carbons with a wide ASA range. The decomposition behavior was evaluated by thermogravimetric analysis (TGA) and evolved gas analysis via mass spectrometry and Fourier transform infrared spectrometry. Higher carbon ASA yields lower decomposition temperatures. SO _x emissions are realized at temperatures as low as 773 K. Isothermal Na₂SO₄–C decomposition initiates via the nucleation of Na₂S. The rate constants for the nucleation regime are normalized against ASA, yielding an activation energy of 275 kJ/mol for nucleation.     

The reaction of 1,2-dichloroethane with copper

The decomposition of 1,2-dichloroethane on polycrystalline copper has been studied using a microreactor. The reaction is found to have an activation energy of 81±5 kJ mol^–1 generating gaseous ethene and chemisorbed chlorine. The reaction terminates on completion of a monolayer of chemisorbed chlorine and is followed by a much slower reaction. The rate limiting step is thought to be C₂H₄Cl_2(phys)C2H₄Cl(_ads)+Cl_ads The reaction is compared with a UHV study of the same molecule on Cu(l 11) and the possibility of a negative ion transition state is discussed.