Recent progress towards the electrosynthesis of ammonia from sustainable resources

Ammonia (NH3) is a key commodity chemical of vital importance for fertilisers. It is made on an industrial scale via the Haber Bosch process, which requires significant infrastructure to be in place such that ammonia is generally made in large, centralized facilities. If ammonia could be produced under less demanding conditions, then there would be the potential for smaller devices to be used to generate ammonia in a decentralized manner for local consumption. Electrochemistry has been proposed as an enabling technology for this purpose as it is relatively simple to scale electrolytic devices to meet almost any level of demand. Moreover, it is possible to envisage electrosynthetic cells where water could be oxidised to produce protons and electrons at the anode which could then be used to reduce and protonate nitrogen to give ammonia at the cathode. If this nitrogen were sourced from the air, then the only required infrastructure for this process would be supplies of water, air and electricity, the latter of which could be provided by renewables. Hence an electrosynthetic cell for ammonia production could allow NH3 to be generated sustainably in small, low-cost devices requiring only minimal facilities. In this review, we describe recent progress towards such electrosynthetic ammonia production devices, summarizing also some of the seminal literature in the field. Comparison is made between the various different approaches that have been taken, and the key remaining challenges in the electrosynthesis of ammonia are highlighted

Communications software performance prediction

Software development can be costly and it is important that confidence in a software system be established as early as possible in the design process. Where the software supports communication services, it is essential that the resultant system will operate within certain performance constraints (e.g. response time). This paper gives an overview of work in progress on a collaborative project sponsored by BT which aims to offer performance predictions at an early stage in the software design process. The Permabase architecture enables object-oriented software designs to be combined with descriptions of the network configuration and workload as a basis for the input to a simulation model which can predict aspects of the performance of the system. The prototype implementation of the architecture uses a combination of linked design and simulation tools

Morphology of Saw Marks in Human Bone: Identification of Class Characteristics

Accurate interpretation of saw marks on human bone is an essential part of tool mark examination in the forensic sciences, but appears neglected in practice and in the forensic sciences literature. With a basic understanding of saws and principals of cutting action, residual saw characteristics remaining on human bone can be recognized and interpreted. Two basic areas of saw cut bones are examined. Kerf floors can be examined in false starts and break away spurs. This area of a cut potentially reveals kerf size, striae patterns, and contour differences. Kerf walls, or the cut cross section of bones, reveal striae specifics such as contour, direction of stroke, and patters of cutting action. These areas of cut bone potentially reveal observable and quantifiable characteristics that can be related to predictable saw actions. These characteristics may indicate distances between saw teeth, type and amount of tooth set, tooth and blade shape, manner in which a saw is powered, and direction of saw cut. These characteristics, utilized individually or in combination, narrow the number of possible saws that potentially create a particular cut. This narrowing of the field of saws allows the examiner to assess the class. subclass, or type of saw utilized in a cut. Ultimately, examination of human bone remains will allow anthropologist to go beyond the descriptive level of analysis to confront modified bone with an appreciation for its potential forensic value

Harris Lines as Indicators of Stress: An Analysis of Tibiae From the Crow Creek Massacre Victims

Horizontal lines of increased density in bone, or Harris lines, have intrigued scientists for over a century. While earliest Harris line research dealt with medical aspects of line formation, most recent emphasis has been anthropological in nature, utilizing Harris lines as non-specific indicators of stress. The purpose of this study is to test the usefulness of Harris lines as they are applied anthropologically. A sample of 122 adult distal tibiae x-rays are used in this study. This skeletal sample represents massacre victims from the Initial Coalescent Tradition of the Crow Creek Site in central South Dakota. Each bone was sexed by discriminant function analysis and age of line formation was estimated. Harris line frequencies reveal no sex differences. However, when age-specific frequencies are compared with sex-specific human growth curves, there is a strong similarity in curve shape. These results suggest that sex influences on line formation are probably subtle but not detectable. The similarity in frequency of line formation and growth velocity has discouraging connotations for the usefulness of Harris lines as indicators of stress

Force Without Law: Seeking a Legal Justification for the September 1996 U.S. Military Intervention in Iraq

This note concludes that none of the various legal arguments offered in support of the September 1996 military intervention against Iraq adequately justifies U.S. actions under international law and that in fact international law was never a real concern in planning, implementing, or even justifying the intervention. Part I relates the general history of the Kurdish problem and the particulars of the incident under scrutiny. This Part then goes on to describe the aftermath of the intervention and its failure to achieve any of the stated goals of the United States. Part II addresses the general validity under international law of military intervention in internal affairs of sovereign states, with particular attention to humanitarian intervention, and concludes that the intervention was contrary to international law. Part III explores the UN position on military intervention, conduct authorized under UN resolutions regarding Iraq and the Kurds, and the legal parameters of the no-fly zones in Iraq, concluding that the intervention was not a valid enforcement of UN policies or resolutions. Part IV critiques the apparent U.S. belief that it can override generally accepted norms of international law by defining its concerns as national security issues. Finally, Part V looks to the practical impact of international law in this matter and what the intervention and its aftermath, including widespread condemnation of the U.S. action, reveal about the geopolitical realities of international law

Observations on the Increasing Malignancy of Tumours on Prolonged Growth: The Influence of Immunological Changes in the Host

Spontaneously occurring A-strain mouse mammary carcinomata were individually passaged, at equal intervals into separate groups of isogenic hosts. The tumours showed evidence of increasing autonomy as judged either by the decreasing host lymphoid hyperplasia they evoked, or their decreased killing time, as passaging continued. However, in general, no reduction was found in the ability of spleen cells from hosts bearing succeeding passages of the same tumour to induce a graft-versus-host reaction in (A × CBA)F1 hybrid mice. It is therefore suggested that the increasing malignancy of the tumours studied was associated with a change in the tumour rather than increasing immunodepression in successive hosts

A re-evaluation of Sn(II) phthalocyanine as a catalyst for the electrosynthesis of ammonia

The electrosynthesis of ammonia from nitrogen and water is a topic of considerable interest in the quest for sustainable and decentralized NH3 production. Tin(II) phthalocyanine complexes have been proposed as electrocatalysts for nitrogen reduction to ammonia in aqueous solution, with Faradaic yields approaching 2% having been reported. Herein, however, we show that such complexes are not electrocatalysts for this transformation, with the amount of ammonia detected being essentially the same under N2 and under Ar. Instead, we suggest that apparent ammonia generation could arise either through contaminants in the as-prepared tin (II) phthalocyanine complexes, or by the electro-decomposition of these complexes under cathodic bias

Further Observations on Whether Host Immunodepression is Associated with Tumour Growth in Mice

In order to investigate whether the presence of a tumour was associated with immunodepression in the host, spleen cells from parent line animals with tumours were injected intravenously into F1 hybrids, half of which carried the same tumour. Further groups of F1 hybrid with and without the tumour received spleen cells from non-tumour bearing parent line animals. The G.V.H. reactions induced in the four groups of F1 hybrid were compared and no significant differences were found. This was true in separate experiments, involving two mammary carcinomata and a 3-methylcholanthrene induced sarcoma, wherein the period of tumour growth in the parent line donor and F1 hybrid recipient was varied

Single-shot optical conductivity measurement of dense aluminum plasmas

The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.DOE National Nuclear Security Administration DE-FC52-03NA00156Physic

Adler-Kostant-Symes systems as Lagrangian gauge theories

It is well known that the integrable Hamiltonian systems defined by the Adler-Kostant-Symes construction correspond via Hamiltonian reduction to systems on cotangent bundles of Lie groups. Generalizing previous results on Toda systems, here a Lagrangian version of the reduction procedure is exhibited for those cases for which the underlying Lie algebra admits an invariant scalar product. This is achieved by constructing a Lagrangian with gauge symmetry in such a way that, by means of the Dirac algorithm, this Lagrangian reproduces the Adler-Kostant-Symes system whose Hamiltonian is the quadratic form associated with the scalar product on the Lie algebra.Comment: 10 pages, LaTeX2