Pyrolysis and oxidation of ethyl methyl sulfide in a flow reactor

The reactions and kinetics of ethyl methyl sulfide (CH₃CH₂SCH₃, abbreviation CCSC), a simulant for the chemical warfare agent sulfur mustard, were studied at temperatures of 630–740 °C, under highly diluted pyrolysis and oxidation conditions at one atmosphere in a turbulent flow reactor. The loss of the ethyl methyl sulfide and the formation of intermediates and products were correlated with time and temperature. Destruction efficiencies of 50% and 99% were observed for pyrolysis and oxidation, respectively, at 740 °C with a residence time of 0.06 s. For pyrolysis, ethylene, ethane, and methane were detected at significant levels. In addition to these species, carbon monoxide, carbon dioxide, sulfur dioxide, and formaldehyde were detected for oxidation. Conversions of ethyl methyl sulfide were observed to be significantly slower than observed previously for diethyl sulfide; explanations for this observation are postulated, based on: (1) lower hydrogen abstraction rates or on (2) lower hydrogen atom production as a result of thermal decomposition pathways. Initial decomposition reactions and production pathways for important species observed in the experiments are discussed on a basis of thermochemistry.     

Analysis of Isinglass Residues in Beer

A method has been developed for the detection of trace quantities of residual isinglass present in fined beers. Isinglass residues in beer are concentrated by means of an antibody raised using isinglass as an antigen. The separated isinglass is hydrolysed to its constituent acids and quantified by measuring the content of hydroxyproline. The limit of quantification of this method, that is the concentration of isinglass in beer which can be distinguished from background levels of hydroxyproline, is 0.17 mg of isinglass/litre of beer (on an isinglass dry weight basis). This method has been used to quantify the concentration of isinglass residues which could be present in brewery and cask conditioned beers, and also to determine whether there is likely to be stratification of isinglass residues in casks.     

Proliferation and functional maturation of Sertoli cells,and their relevance to disorders of testis function in adulthood

Disorders of testicular function may have their origins in fetal or early life as a result of abnormal development or proliferation of Sertoli cells. Failure of Sertoli cells to mature, with consequent inability to express functions capable of supporting spermatogenesis, is a prime example. In a similar way, failure of Sertoli cells to proliferate normally at the appropriate period in life will result in reduced production of spermatozoa in adulthood. This review focuses on the control of proliferation of Sertoli cells and functional maturation, and is motivated by concerns about 'testicular dysgenesis syndrome' in humans, a collection of common disorders (testicular germ-cell cancer, cryptorchidism, hypospadias and low sperm counts) which are hypothesized to have a common origin in fetal life and to reflect abnormal function of Sertoli (and Leydig) cells. The timing of proliferation of Sertoli cells in different species is reviewed, and the factors that govern the conversion of an immature, proliferating Sertoli cell to a mature, non-proliferating cell are discussed. Protein markers of maturity and immaturity of Sertoli cells in various species are reviewed and their usefulness in studies of human testicular pathology are discussed. These markers include anti-Mullerian hormone, aromatase, cytokeratin-18, GATA-1, laminin alpha5, M2A antigen, p27(kip1), sulphated glycoprotein 2, androgen receptor and Wilms' tumour gene. A scheme is presented for characterization of Sertoli-cell only tubules in the adult testis according to whether or not there is inherent failure of maturation of Sertoli cells or in which the Sertoli cells have matured but there is absence, or acquired loss, of germ cells. Functional 'de-differentiation' of Sertoli cells is considered. It is concluded that there is considerable evidence to indicate that disorders of maturation of Sertoli cells may be a common underlying cause of human male reproductive disorders that manifest at various life stages. This recognition emphasizes the important role that animal models must play to enable identification of the mechanisms via which failure of proliferation and maturation of Sertoli cells can arise, as this failure probably occurs in fetal life.     

Muscularity and eating quality of lambs: Effects of breed, sex and selection of sires using muscularity measurements by computed tomography

Differences in muscularity of the hind leg (HL) and lumbar region (LR) were investigated between sexes (ram vs ewe lambs), breeds (Scottish Blackface, SBF vs Texel, TEX) and progeny of high- and low-muscularity sires (HM, LM) (n=471). The influence of these factors on meat eating quality (MEQ) was also examined (n=229). TEX lambs had 16% greater muscularity than SBF in both regions, whilst differences between sire groups were 4%. Ewe lambs had slightly higher values of muscularity for the HL than rams, but values were similar for the LR. Meat from SBF lambs had higher tenderness, stronger lamb flavour and higher overall liking than TEX meat. Sex had a weak influence with ram lambs having a stronger abnormal flavour and lower overall liking in the LR only. No significant differences in MEQ were found between HM- and LM-sired lambs, suggesting that improvements in muscularity would not have unfavourable effects on MEQ.     

1 kWe sodium borohydride hydrogen generation system: Part I: Experimental study

A 1 kW_e hydrogen generation system using hydrolysis of sodium borohydride (NaBH₄) has been designed and built. The effects of flow rate, fuel concentration, inlet temperature and operating pressure on chemical conversion have been systematically investigated. A 10-point thermocouple profile probe was used to measure the temperature distribution inside the catalyst bed. Chemical conversion was also qualitatively evaluated via the temperature profile. For the present adiabatic reactor, a large temperature gradient at the outlet implies low conversion, while a small temperature gradient at the outlet implies high conversion. In order to obtain accurate measurements of hydrogen flow rate, water vapor carried in the product stream was removed by a custom hydrogen conditioning station. Using 15% concentration NaBH₄ aqueous solution, this system generated hydrogen up to 20 SLPM with a reasonably high chemical conversion (95%). Discharge products from using NaBH₄ concentrations above 15% crystallized upon cooling to room temperature. Such products would be difficult to remove from the discharge tank in a practical setting. Considering the practical difficulties in heating the discharge product to prevent crystallization, the highest usable concentrations would likely fall in the range of 10–15%. The resulting maximum material gravimetric density is 3.1 wt% of hydrogen and falls short of the DOE on-board hydrogen storage system target of 6 wt% for year 2010.     

1 kWe sodium borohydride hydrogen generation system: Part II: Reactor modeling

Sodium borohydride (NaBH₄) hydrogen storage systems offer many advantages for hydrogen storage applications. The physical processes inside a NaBH₄ packed bed reactor involve multi-component and multi-phase flow and multi-mode heat and mass transfer. These processes are also coupled with reaction kinetics. To guide reactor design and optimization, a reactor model involving all of these processes is desired. A one-dimensional numerical model in conjunction with the assumption of homogeneous catalysis is developed in this study. Two submodels have been created to simulate non-isothermal water evaporation processes and pressure drop of two-phase flow through the porous medium. The diffusion coefficient of liquid inside the porous catalyst pellets and the mass transfer coefficient of water vapor are estimated by fitting experimental data at one specified condition and have been verified at other conditions. The predicted temperature profiles, fuel conversion, relative humidity and pressure drops match experimental data reasonably well.     

Effect of pelvic suspension on three major leg muscles in the pig carcass and implications for ham manufacture

Thirty-two female pigs were slaughtered and their left sides suspended conventionally by the Achilles tendon whilst right sides were suspended from the pelvic bone. The first 16 pigs were used to measure suspension effects on the characteristics of three major leg muscles (m. gluteobiceps, m. semimembranosus and m. rectus femoris) and to assess their suitability for ham manufacture. The remaining pigs were used for the production of hams, made from tunnel- boned whole legs injected to a target 10% weight gain, then tumbled and cooked. Compared with conventional hanging, pelvic suspension resulted in significantly (P<0.01) lower weight loss from the sides during chilling (2.8 and 2.5%). There were major changes in the shape of all three muscles, with pelvic suspension producing marked increases in the width of the m. gluteobiceps (24%) and length of the m. semimembranosus (34%), and a small reduction in the length of the m. rectus femoris (2%). It also resulted in the two former muscles having a relatively higher brine retention, lower drip losses after storage and lower instrumental texture values (Volodkevitch shear force). Cooking loss was reduced in the pelvic-suspended m. semimembranosus. Similarly, whole gammon hams made from pelvic-suspended sides had greater injection gains than hams from conventionally-hung sides (13.6 and 12.3%), with lower cooking losses (16.7 and 19.0%). Instrumental texture values (punch and die peak force) made on the individual muscles in 3-mm thick slices were lower for the m. gluteobiceps (5914 and 9085 g) and m. semimembranosus (6163 and 7600 g) as a result of pelvic suspension. There were minor but significant effects on some colour parameters which probably have little commercial impact. The results demonstrate the advantages of pelvic suspension in terms of brine uptake and retention, and hence increased yield, as well as reduced toughness, for at least two of the major leg muscles, m. gluteobiceps and m. semimembranosus, with no disadvantage for the m. rectus femoris. Together, these three muscles constitute about half of the trimmed leg weight.     

Fixed access network technologies

Telecommunications operators around the world are facing flat or declining revenues in their traditional services and expanding commercial and political demand for ubiquitous broadband access. This creates two opposing pressures — to cut costs radically and to invest heavily in new technology. The traditional fixed access network is central to both of these issues and this paper describes the technology that is being developed to meet these challenges.     

First-Order Temporal Verification in Practice

First-order temporal logic, the extension of first-order logic with operators dealing with time, is a powerful and expressive formalism with many potential applications. This expressive logic can be viewed as a framework in which to investigate problems specified in other logics. The monodic fragment of first-order temporal logic is a useful fragment that possesses good computational properties such as completeness and sometimes even decidability. Temporal logics of knowledge are useful for dealing with situations where the knowledge of agents in a system is involved. In this paper we present a translation from temporal logics of knowledge into the monodic fragment of first-order temporal logic. We can then use a theorem prover for monodic first-order temporal logic to prove properties of the translated formulas. This allows problems specified in temporal logics of knowledge to be verified automatically without needing a specialized theorem prover for temporal logics of knowledge. We present the translation, its correctness, and examples of its use. Partially supported by EPSRC project: Analysis and Mechanisation of Decidable First-Order Temporal Logics (GR/R45376/01).     

Software engineering: An example of misuse

Managers of programmers and designers are sometimes wont to adopt the new and shiny. This paper describes a situation in which managers at several levels grasped for the ‘new and shiny’ in the form of software engineering. This approach was not without its hidden dangers, especially when established guidelines were ignored or violated. The results of an experience with a large software project are reported. This project dealt with a sophisticated inventory control system. The effects on the project of ignorance and the violation of rules are described. Several measures of the final product are reported. Observations of the authors conclude the paper.