Interfacial structures and energetics of the strengthening precipitate phase in creep-resistant Mg-Nd-based alloys

The extraordinary creep-resistance of Mg-Nd-based alloys can be correlated to the formation of nanoscale-platelets of β₁-Mg₃Nd precipitates, that grow along 〈110〉_Mg in bulk hcp-Mg and on dislocation lines. The growth kinetics of β₁ is sluggish even at high temperatures, and presumably occurs via vacancy migration. However, the rationale for the high-temperature stability of precipitate-matrix interfaces and observed growth direction is unknown, and may likely be related to the interfacial structure and excess energy. Therefore, we study two interfaces– {112}_β1/{100}_Mg and {111}_β1/{110}_Mg– that are commensurate with β₁/hcp-Mg orientation relationship via first principles calculations. We find that β₁ acquires plate-like morphology to reduce small lattice strain via the formation of energetically favorable {112}_β1/{100}_Mg interfaces, and predict that β₁ grows along 〈110〉_Mg on dislocation lines due to the migration of metastable {111}_β1/{110}_Mg. Furthermore, electronic charge distribution of the two interfaces studied here indicated that interfacial-energy of coherent precipitates is sensitive to the population of distorted lattice sites, and their spatial extent in the vicinity of interfaces. Our results have implications for alloy design as they suggest that formation of β₁-like precipitates in the hcp-Mg matrix will require well-bonded coherent interface along precipitate broad-faces, while simultaneously destabilizing other interfaces.

Thoracoscopic lobectomy: comparison of intraoperative and postoperative outcomes between 3 and 4 incision accesses

AIMS AND BACKGROUND

Several techniques have been proposed to perform a video-assisted thoracic lobectomy. We compared the results of a 3 versus 4-port procedure, analyzing intraoperative data, morbidity, and mortality.

METHODS

Prospective analysis of 30 consecutive patients who underwent a 4-port approach video-assisted thoracic lobectomy (group A) and comparison with a historical series with 30 patients who had a 3-port video-assisted thoracic lobectomy (group B).

RESULTS

The groups were comparable for clinical characteristics and pathological staging. There was no difference in operating time: median, 128 min for group A versus 129 min for group B (P = 0.9). There was a significant difference in rate of conversion to thoracotomy: 1 of 30 (3.3%) in group A and 7 of 30 (23.3%) in group B (3 ports) (P = 0.02). In group A, 11 patients (36.7%) experienced postoperative complications and in group B, 13 patients (43.3%; P = 0.6). The difference in median time to drain removal and median length of hospital stay between the two groups was not significant. There was a significant difference in persistent pain between group A and group B: 6 patients (20%) in group B presented with persistent neuropathic pain on regular medication (P = 0.02).

CONCLUSIONS

Our study showed that the 4-port approach was similar in operative time, length of drain and hospital stay but showed a statistically significant lower conversion rate and lower rate of persistent pain than the 3-port access.

Thoracoscopic Lobectomy: Comparison of Intraoperative and Postoperative Outcomes between 3 and 4 Incision Accesses

Aims and background

Several techniques have been proposed to perform a video-assisted thoracic lobectomy. We compared the results of a 3 versus 4-port procedure, analyzing intraoperative data, morbidity, and mortality.

Methods

Prospective analysis of 30 consecutive patients who underwent a 4-port approach video-assisted thoracic lobectomy (group A) and comparison with a historical series with 30 patients who had a 3-port video-assisted thoracic lobectomy (group B).

Results

The groups were comparable for clinical characteristics and pathological staging. There was no difference in operating time: median, 128 min for group A versus 129 min for group B (P = 0.9). There was a significant difference in rate of conversion to thoracotomy: 1 of 30 (3.3%) in group A and 7 of 30 (23.3%) in group B (3 ports) (P = 0.02). In group A, 11 patients (36.7%) experienced postoperative complications and in group B, 13 patients (43.3%; P = 0.6). The difference in median time to drain removal and median length of hospital stay between the two groups was not significant. There was a significant difference in persistent pain between group A and group B: 6 patients (20%) in group B presented with persistent neuropathic pain on regular medication (P = 0.02).

Conclusions

Our study showed that the 4-port approach was similar in operative time, length of drain and hospital stay but showed a statistically significant lower conversion rate and lower rate of persistent pain than the 3-port access.

Psychiatric aspects of acute withdrawal from gamma-hydroxybutyrate (GHB) and its analogue gamma-butyrolactone (GBL): implications for psychiatry services in the general hospital

OBJECTIVE

The objective of this study was to describe the psychiatric symptoms, management and outcomes in a consecutive series of patients being managed medically for symptoms of withdrawal from gamma-hydroxybutyrate (GHB) and its analogue gamma-butyrolactone (GBL) in a general hospital setting.

METHODS

A toxicology database was used to identify patients presenting with a history suggestive of withdrawal from GHB and analogues. Electronic and paper medical records were searched for demographic features, neuropsychiatric symptoms, psychiatric management while in hospital and overall outcome.

RESULTS

There were 31 presentations with withdrawal from the drugs involving 20 patients. Of these 17 (54%) were referred to and seen by the liaison psychiatry team. Anxiety (61.3%) and agitation (48.4%) were the most common symptoms. Of the 17 cases seen by the liaison psychiatry team, 52.9% required close constant observation by a mental health nurse and 29.4% required to be detained in hospital under mental health legislation.

CONCLUSIONS

The significant proportion of patients presenting with neuropsychiatric symptoms and requiring intensive input from the liaison psychiatry team during withdrawal from GHB and its analogues points to the importance of close liaison between medical and psychiatric teams in managing these patients in the general hospital.

An evaluation of emerging vaccines for childhood meningococcal disease

Background

Meningococcal meningitis is a major cause of disease worldwide, with frequent epidemics particularly affecting an area of sub-Saharan Africa known as the “meningitis belt”. Neisseria meningitidis group A (MenA) is responsible for major epidemics in Africa. Recently W-135 has emerged as an important pathogen. Currently, the strategy for control of such outbreaks is emergency use of meningococcal (MC) polysaccharide vaccines, but these have a limited ability to induce herd immunity and elicit an adequate immune response in infant and young children. In recent times initiatives have been taken to introduce meningococcal conjugate vaccine in these African countries. Currently there are two different types of MC conjugate vaccines at late stages of development covering serogroup A and W-135: a multivalent MC conjugate vaccine against serogroup A,C,Y and W-135; and a monovalent conjugate vaccine against serogroup A. We aimed to perform a structured assessment of these emerging meningococcal vaccines as a means of reducing global meningococal disease burden among children under 5 years of age.

Methods

We used a modified CHNRI methodology for setting priorities in health research investments. This was done in two stages. In the first stage we systematically reviewed the literature related to emerging MC vaccines relevant to 12 criteria of interest. In Stage II, we conducted an expert opinion exercise by inviting 20 experts (leading basic scientists, international public health researchers, international policy makers and representatives of pharmaceutical companies). They answered questions from CHNRI framework and their “collective optimism” towards each criterion was documented on a scale from 0 to 100%.

Results

For MenA conjugate vaccine the experts showed very high level of optimism (~ 90% or more) for 7 out of the 12 criteria. The experts felt that the likelihood of efficacy on meningitis was very high (~ 90%). Deliverability, acceptability to health workers, end users and the effect on equity were all seen as highly likely (~ 90%). In terms of the maximum potential impact on meningitis disease burden, the median potential effectiveness of the vaccines in reduction of overall meningitis mortality was estimated to be 20%; (interquartile range 20-40% and min. 8%, max 50 %). For the multivalent meningococcal vaccines the experts had similar optimism for most of the 12 CHNRI criteria with slightly lower optimism in answerability and low development cost criteria. The main concern was expressed over the cost of product, its affordability and cost of implementation.

Conclusions

With increasing recognition of the burden of meningococcal meningitis, especially during epidemics in Africa, it is vitally important that strategies are taken to reduce the morbidity and mortality attributable to this disease. Improved MC vaccines are a promising investment that could substantially contribute to reduction of child meningitis mortality world-wide.

Selection response for part period egg number and egg mass in chickens - a comparison

Two sublines from each of four flocks of White Leghorn were subjected to two cycles of selection for part year egg number and part year egg mass. A family index (combined selection) was the selection criterion for each of the two traits. The generation means of an unselected pedigreed randombred control, bred and maintained along with the selected sub-lines, were used for correcting short term environmental trends. The sublines selected for a common selection criterion were considered as replicates. The control corrected generation means, when averaged over replicates, gave the mean direct and correlated responses for the selected and different unselected traits. The average genetic change per generation was 2.16 eggs in egg number selected sublines and 146 g of egg mass in egg mass selected sublines. The direct response marginally exceeded the correlated response for both part period egg number and egg mass seen in the corresponding sublines. Except for egg weight the correlated responses for different unselected traits were in the same direction in both egg number and egg mass selected sublines. While the egg weight in egg number lines did not change, its response was positive in egg mass selected lines. A comparison between the lines revealed that the egg mass selected lines matured later and laid heavier but slightly less numerous eggs than the egg number selected sub-lines.

Selection for egg production on part records : Part 2. Correlated response to selection

Response in the selected and the correlated traits from five generations of index selection (I.D.S. method) for egg production to 40 weeks of age in four White Leghorn populations have been presented. The correlated traits measured included: Age at first egg, egg weight, body weight and also derived traits such as egg mass, survivors' rate of lay, efficiency index and ratio of egg weight to body weight. Response realized for the selected trait was significant in three out of the four selected lines. Predicted and realized genetic gains were comparable in magnitude for most of the traits studied. The significance of these findings in selection experiments is discussed.

Selection for egg production on part records : Part 1: Evaluation of short term response to selection

Responses from four generations of index selection for egg production to 280 days of age in four White Leghorn populations have been presented. A pedigreed randombred population derived from one of the lines was reared with the selected lines to measure the environmental trend. The magnitude of total as well as average response although varying from population to population was positive in all the lines studied. Close correspondence between predicted and realized gains indicated that natural selection, genotype environmental interactions and environmental fluctuations were unimportant during the course of selection. Realized heritabilities agreed fairly well with the estimated heritabilities in at least three out of four populations studied. Probable reasons for variable and insufficient response were investigated.