Oxidation of GaN: An ab initio thermodynamic approach

GaN is a wide-bandgap semiconductor used in high-efficiency LEDs and solar cells. The solid is produced industrially at high chemical purities by deposition from a vapour phase, and oxygen may be included at this stage. Oxidation represents a potential path for tuning its properties without introducing more exotic elements or extreme processing conditions. In this work, ab initio computational methods are used to examine the energy potentials and electronic properties of different extents of oxidation in GaN. Solid-state vibrational properties of Ga, GaN, Ga2O3 and a single substitutional oxygen defect have been studied using the harmonic approximation with supercells. A thermodynamic model is outlined which combines the results of ab initio calculations with data from experimental literature. This model allows free energies to be predicted for arbitrary reaction conditions within a wide process envelope. It is shown that complete oxidation is favourable for all industrially-relevant conditions, while the formation of defects can be opposed by the use of high temperatures and a high N2:O2 ratio

The game is up: proposals on incorporating effective case management into criminal investigations

Over recent years, there has been a marked change in the handling of criminal cases before the Courts. The introduction of the Criminal Procedure Rules in 2005, along with initiatives such as Simple Speedy Summary Justice and more recently, Stop Delaying Justice, has created a shift away from slow moving cases and ambush defences. As a result, there is a presumption that criminal cases will progress from the very first hearing, fewer hearings are being adjourned and advocates on both sides are expected to be better prepared and ready to disclose their case from the outset. This paper will present an argument that it is now time to bring the principles behind these initiatives into the investigation stage of proceedings. By promoting better case management from the point of arrest, it is submitted that delays in resolving cases can be even further reduced, without affecting, but potentially improving fairness for all parties. Whilst the disclosure is given by many investigators, there is currently no rule that states that disclosure must be given at the police station stage. The authors contend that a requirement to provide disclosure at the police station, even in summary form, will allow more effective advice to be given to suspects and in turn improve the interview process. Early disclosure should prevent delays in bringing cases before the court and will also assist in ensuring that progress is made at the first hearing. Furthermore, by avoiding the need for unnecessary police bail appointments, and timely charging procedures, it is contended that summary justice can be achieved efficiently, fairly and in a manner that reduces tactical considerations in the police station

Sizing up nanoelectronics: gauging the potential for new productivity wave

The Federal Reserve Bank of Dallas, in cooperation with the Semiconductor Industry Association (SIA), hosted a conference on nanoelectronics and the economy in Austin on Dec. 3, 2010. Economists and scientists explored how information technology has affected U.S. productivity and output growth and prospects for the future.Technological innovations ; Productivity

A universal chemical potential for sulfur vapours

The unusual chemistry of sulfur is illustrated by the tendency for catenation. Sulfur forms a range of open and closed S$_n$ species in the gas phase, which has led to speculation on the composition of sulfur vapours as a function of temperature and pressure for over a century. Unlike elemental gases such as O$_2$ and N$_2$, there is no widely accepted thermodynamic potential for sulfur. Here we combine a first-principles global structure search for the low energy clusters from S$_2$ to S$_8$ with a thermodynamic model for the mixed-allotrope system, including the Gibbs free energy for all gas-phase sulfur on an atomic basis. A strongly pressure-dependent transition from a mixture dominant in S$_2$ to S$_8$ is identified. A universal chemical potential function, $\mu_{\mathrm{S}}(T,P)$, is proposed with wide utility in modelling sulfurisation processes including the formation of metal chalcogenide semiconductors.Comment: 12 pages, 9 figures. Supporting code and data is available at https://github.com/WMD-Bath/sulfur-model [snapshot DOI: 10.5281/zenodo.28536]. Further data will be available from DOI:10.6084/m9.figshare.1513736 and DOI:10.6084/m9.figshare.1513833 following peer-revie

Expert Evidence in Criminal Proceedings: Current challenges and opportunities

In its 2011 report “Expert Evidence in Criminal Proceedings in England and Wales” (Law Com No.325), the Law Commission recommended that the admissibility of expert evidence in criminal proceedings should be governed by a new statutory regime comprising a new statutory reliability test in combination with codification and refinement of existing common law principles relating to “assistance”, “expertise” and “impartiality”. The Government declined to enact the Law Commission’s draft Bill due to a lack of certainty as to whether the additional costs incurred would be offset by savings. Instead the Government invited the Criminal Procedure Rule Committee (CrimPRC) to consider amendments to the Criminal Procedure Rules (CrimPR) to introduce, as far as possible, the spirit of the Law Commission’s recommendations. The consequent amendments to CrimPR Part 33 (now CrimPR Part 19) in combination with the making of the new Practice Direction CrimPD 33A (now CrimPD 19A) by the Lord Chief Justice, resulted in what he described in his 2014 Criminal Bar Association Kalisher Lecture as “a novel way of implementing an excellent Report”. This paper considers the possible evolution of the common law in light of these amendments, the challenges associated with adopting such a novel approach to reform and the potential opportunities for the improvement of expert evidence in criminal proceedings that the changes were intended to create

Making the case for ECRIS: Post “Brexit” sharing of criminal records information between the European Union and United Kingdom

Criminal record information has various uses including, in the detection of crime, as evidence in criminal proceedings, in consideration of an appropriate sentence after conviction and in determining the suitability of an individual for, or providing a bar to, employment. As such this information can have a high value but can also significantly interfere with a person’s right to private and family life under Article 8 of the European Convention on Human Rights. The importance of Article 8 in this area has been increasingly recognised in both domestically and in Strasbourg with such case law making clear the imperative that criminal record information is accurate, retained and disclosed only in proper circumstances and, where appropriate, is capable of being subject to proper challenge. The operation of the European Criminal Records Information System (ECRIS) for exchange of criminal records between member states is explored and the benefits and risks of exchanging criminal records information within such an automated system are identified. The compliance of ECRIS to Article 8 ECHR is considered and suggestions made for future improvements. Evidence is provided that ECRIS constitutes a singular improvement on earlier ad-hoc arrangements and should therefore be retained by the United Kingdom post-Brexit

Culpability compared: Mental capacity, criminal offences and the role of the expert in common law and civil law jurisdictions

This article compares the situation in which an individual with diminished mental capacity is prosecuted for a criminal offence in England and Wales and in the Netherlands, with a particular focus on the role of the expert medical witness. It is not unreasonable to assume that, whatever the jurisdiction, the existence of a condition affecting the mental capacity of the defendant may affect how the culpability of the accused is assessed by the courts and translated into a verdict. By comparing culpability in the context of the role of experts, consideration will be given to how substantive and procedural law hang together in the different jurisdictions. A comparison between England and Wales (as an example of a common law jurisdiction) and the Netherlands (as an example of a civil law jurisdiction) may reveal very different outcomes with regard to the verdict and the way it is reached that have far-reaching consequences for the person involved. This article will examine why such differences may occur, in particular whether they are the result of the common law’s reliance on just two possible reasons for the absence of culpability in such cases (insanity or automatism, or, conceivably, diminished responsibility if murder is the charge), while the civil law is based on a theoretically underpinned doctrine that allows for a greater range of defences with regard to culpability (and its relative absence) in general. The topic not only has possible practical implications, but could also contribute to the growing body of comparative scholarship: comparisons of substantive criminal law, unlike its many procedural aspects, are few and far between. One of the reasons is that substantive law is shot through with moral considerations that are very difficult to ascertain and muddy the comparative waters considerably. In this case, however, the issue is not the offence itself, but whether and how a mental condition may affect culpability. While it could be said that the recognition of such conditions is also contingent on their social and moral connotations, the effect of this is likely to be much less than in a comparison of (perpetrators) of sexual offences per se

Sexual behaviour evidence and evidence of bad character in sexual offence proceedings: Proposing a combined admissibility framework.

This article critically evaluates whether the ‘rape shield’ legislation in England and Wales, as currently contained in s 41 Youth Justice and Criminal Evidence Act (YJ&CEA) 1999, is fit for purpose. The article addresses the impact of the case of R v Evans (Chedwyn) [2016] EWCA Crim 452 which received a disproportionately high amount of media scrutiny and led to subsequent calls for greater restrictions on sexual behaviour evidence. The article examines possible reform proposals by Findlay Stark and Matt Thomason and the results of empirical research conducted by Laura Hoyano before proposing the introduction of a ‘combined admissibility framework’ for evidence of a complainant’s previous sexual behaviour and bad character. The proposed framework seeks to retain the high threshold for the admissibility, in particular, of evidence relating to a complainant’s previous sexual behaviour while introducing a more holistic and straightforward model moving away from the strict categories approach adopted by s 41 YJ&CEA 1999