Transformer Oil Passivation and Impact of Corrosive Sulphur

In recent years a significant volume of research has been undertaken in order to understand the recent failures in oil insulated power apparatus due to deposition of copper sulphide on the conductors and in the insulation paper. Dibenzyl Disulfide (DBDS) has been found to be the leading corrosive sulphur compound in the insulation oil [1]. The process of copper sulphide formation and the deposition in the paper is still being investigated, but a recently proposed method seems to be gaining some confidence [1]. This method suggests a two-step process; initially the DBDS and some oil soluble copper complexes are formed. Secondly the copper complexes are absorbed in the paper insulation, where they then decompose into copper sulphide [2]. The most commonly used mitigating technique for corrosive sulphur contaminated oil is passivation, normally using Irgamet 39 or 1, 2, 3-benzotriazole (BTA). The passivator is diluted into the oil to a concentration of around 100ppm, where it then reacts with the copper conductors to form a complex layer around the copper, preventing it from interacting with DBDS compounds and forming copper sulphide. This research project will investigate the electrical properties of HV transformers which have tested positive for corrosive sulphur, and the evolution of those properties as the asset degrades due to sulphur corrosion. Parallel to this the long term properties of transformers with passivated insulation oil will be analysed in order to understand the passivator stability and whether it is necessary to keep adding the passivator to sustain its performance. Condition monitoring techniques under investigation will include dielectric spectroscopy, frequency response analysis, recovery voltage method (aka interfacial polarisation) amongst others. Partial discharge techniques will not be investigated, as the voltage between the coil plates is low and therefore it will not contribute significantly to the overall insulation breakdown, in corrosive oil related faults [3]. The goal of this research is to establish key electrical properties in both passivated and non-passivated power transformers that demonstrate detectable changes as the equipment degrades due to the insulation oil being corrosive

Black dyes for coir fibre: 3 practical considerations

Earlier trials on Synacril Black A, Benzamin Black DS 167% and Suprexcel Black VY- three possible substitute dyes for Chlorazol Black E -showed the effect of variations in dyebath conditions on the amount of dye deposited on coir (Canning, A. J., Jarman, C. G. and Mykoluk, S. M. (1979) Black dyes for coir fibre. Part 2. Evaluation of selected dyes. Report of the Tropical Products Institute, L52). Further trials, in which both different concentrations of dye in the bath, and a standing bath were used, have now been carried out to obtain additional data on the exhaustion characteristics of the three dyes. Additionally, the effect of variations in dyebath conditions on the quality of colour, and the amount of each of the three dyes that needs to be deposited on to the fibre to produce an acceptable black, have been assessed. With all three dyes, dyebath exhaustion was approached more slowly with increased dyebath concentration. As a consequence, when additional dye is used, dyeing time must be increased to obtain the most efficient use of dye. Since the proportion of dye that exhausts from the bath is also reduced, particularly with the higher dyebath concentrations or the shorter dyeing times, increasingly large additions of dye are required in order to intensify the visual depth of shade. With low dyebath concentrations of the two direct dyes (Benzamin Black and Suprexcel Black), allowing the liquor to cool during dyeing could reduce heating costs since the exhaustion obtained after 1.5 hours at 95°C followed by cooling was similar to that obtained after 6 hours at 95°C. However, with deeper shades the opportunity for reducing heating costs by reducing dyeing time at 95°C and then cooling is less. The inclusion of sodium carbonate in the dyebath could also result in savings on dyestuff. When using a standing bath technique with Benzamin Black, significantly different exhaustion/time relationships were obtained with each batch of fibre. As a consequence there would be considerable practical difficulties in using this dye with this technique. On the other hand, the exhaustion of Suprexcel Black was only slightly affected by the use of replenished liquors and a standing bath technique could reduce costs. Because of its almost complete exhaustion, there would be no advantage in using a standing bath with the basic dye Synacril Black. All the dyes gave better light-fastness properties when they were concentrated at the periphery of the fibre rather than when they penetrated more deeply: however, staining of adjacent fabrics was greater. The distribution of the dye within the fibre did not affect the visual colour. All three dyes should produce black colours which are technically similar to those of commercial samples of black coir. The amounts which need to be deposited on the fibre to produce an acceptable black are estimated as approximately: Benzamin Black DS 167% - 19g per kilogram of fibre; Suprexcel Black VY - 22g per kilogram of fibre; Synacril Black A - 10g per kilogram of fibre. Fastness properties of the blacks vary with the dye and the technique used to apply it. Information on the development of optimum dyeing conditions is appended

Service use preceding and following first referral for psychiatric emergency care at a short-stay crisis unit: A cohort study across three cities and one rural area in England

Background: Internationally, hospital-based short-stay crisis units have been introduced to provide a safe space for stabilisation and further assessment for those in psychiatric crisis. The units typically aim to reduce inpatient admissions and psychiatric presentations to emergency departments. Aims: To assess changes to service use following a service user’s first visit to a unit, characterise the population accessing these units and examine equality of access to the units. Methods: A prospective cohort study design (ISCTRN registered; 53431343) compared service use for the 9 months preceding and following a first visit to a short-stay crisis unit at three cities and one rural area in England. Included individuals first visited a unit in the 6 months between 01/September/2020 and 28/February/2021. Results: The prospective cohort included 1189 individuals aged 36 years on average, significantly younger (by 5–13 years) than the population of local service users (<.001). Seventy percent were White British and most were without a psychiatric diagnosis (55%–82% across sites). The emergency department provided the largest single source of referrals to the unit (42%), followed by the Crisis and Home Treatment Team (20%). The use of most mental health services, including all types of admission and community mental health services was increased post discharge. Social-distancing measures due to the COVID-19 pandemic were in place for slightly over 50% of the follow-up period. Comparison to a pre-COVID cohort of 934 individuals suggested that the pandemic had no effect on the majority of service use variables. Conclusions: Short-stay crisis units are typically accessed by a young population, including those who previously were unknown to mental health services, who proceed to access a broader range of mental health services following discharge

Pad-batch dyeing of plant fibres

This guide describes a new method of dyeing plant fibres which are to be made into hats and handbags and other craft work. The pages on this side of the book are intended as a guide for the instructor and extension worker to help him introduce the method to craft workers. We hope the booklet will also be of use to the craft dyers and workers themselves so we have designed the left-hand pages specially for them. The left-hand pages describe the method in photographs with short, clear instructions. The right-hand pages give more information and will help extension workers and instructors to understand and explain the method

Exploring the cytotoxicity, uptake, cellular response, and proteomics of mono- and dinuclear DNA light-switch complexes

Drug resistance to platinum chemotherapeutics targeting DNA often involves abrogation of apoptosis, and has emerged as a significant challenge in modern, non-targeted chemotherapy. Consequently, there is great interest in the anti-cancer properties of metal complexes - particularly those that interact with DNA - and mechanisms of consequent cell death. Herein we compare a parent cytotoxic complex [Ru(phen)2(tpphz)]2+ [phen = 1,10-phenanthroline, tpphz = tetrapyridyl [3,2-a:2',3'-c:3'',2''-h:2''',3'''-j] phenazine], with a mononuclear analogue with modified intercalating ligand, [Ru(phen)2(taptp)]2+,[taptp = 4,5,9,18-tetraazaphenanthreno[9,10-b] triphenylene], and two structurally related di-nuclear, tpphz-bridged, heterometallic complexes, RuRe and RuPt. These changes result in a switch from intercalation to groove binding DNA interaction, concomitant reduction in cytotoxic potency, but no significant change in relative cytotoxicity toward platinum-resistant A2780CIS cancer cells, indicating that DNA interaction mode is not critical for the mechanism of platinum resistance. All variants exhibited a light-switch effect, which for the first time, was exploited to investigate timing of cell death by live cell microscopy. Surprisingly, cell death occurred rapidly as a consequence of oncosis, characterized by loss of cytoplasmic volume control, absence of significant mitochondrial membrane potential loss, and lack of activation of apoptotic cell death markers. Importantly, a novel, quantitative proteomic analysis of the A2780 cell genome following exposure to either mononuclear complex reveals changes in protein expression associated with global cell responses to oxidative stress, and DNA replication/repair cellular pathways. This combination of a multiple targeting modality and induction of a non-apoptotic death mechanism makes these complexes highly promising chemotherapeutic cytotoxicity leads

Validity and worth in the science curriculum: learning school science outside the laboratory

It is widely acknowledged that there are problems with school science in many developed countries of the world. Such problems manifest themselves in a progressive decline in pupil enthusiasm for school science across the secondary age range and the fact that fewer students are choosing to study the physical sciences at higher levels and as careers. Responses to these developments have included proposals to reform the curriculum, pedagogy and the nature of pupil discussion in science lessons. We support such changes but argue from a consideration of the aims of science education that secondary school science is too rooted in the science laboratory; substantially greater use needs to be made of out-of-school sites for the teaching of science. Such usage should result in a school science education that is more valid and more motivating and is better at fulfilling defensible aims of school science education. Our contention is that laboratory-based school science teaching needs to be complemented by out-of-school science learning that draws on the actual world (e.g. through fieldtrips), the presented world (e.g. in science centres, botanic gardens, zoos and science museums) and the virtual worlds that are increasingly available through information and communications technologies (ICT)

The psychiatric decision unit as an emerging model in mental health crisis care: a national survey in England

Psychiatric decision units have been developed in many countries internationally to address the pressure on inpatient services and dissatisfactory, long waits people in mental health crisis can experience in emergency departments. Research into these units lags behind their development, as they are implemented by healthcare providers to address these problems. This is the first-ever national survey to identify their prevalence, structure, activities, and contextual setting within health services, in order to provide a robust basis for future research. The response rate was high (94%), and six PDUs in England were identified. The results indicated that PDUs open 24/7, accept only voluntary patients, provide recliner chairs for sleeping rather than beds, and limit stays to 12–72 hours. PDUs are predominantly staffed by senior, qualified mental health nurses and healthcare assistants, with psychiatry input. Staff:patient ratios are high (1:2.1 during the day shift). Differences in PDU structure and activities (including referral pathway, length of stay, and staff:patient ratios) were identified, suggesting the optimal configuration for PDUs has not yet been established. Further research into the efficacy of this innovation is needed; PDUs potentially have a role in an integrated crisis care pathway which provides a variety of care options to service users