A structural and reactivity study of lithium molybdenum nitride

This thesis describes the preparation and reactivity of lithium molybdenum nitride samples and the preparation and characterisation of the nitride precursors. It has been shown that samples containing lithium molybdenum nitride (LiMoN2) can be formed from the direct ammonolysis of lithium molybdate (Li2MoO4), although it has proved challenging to produce the nitride as a single phase material. The “LiMoN2” samples were observed to be catalytically active for ammonia synthesis in reaction with nitrogen containing feed gas (25% N2/H2). An impurity, which cannot be indentified through powder X-ray diffraction, was demonstrated to be the likely active phase in the sample. The role of ‘lattice’ nitrogen in the ammonia synthesis reaction was investigated through reactions with a feed gas with no source of nitrogen present (25% Ar/H2). It was shown that this proposed active phase will produce ammonia, in the absence of nitrogen in the feed gas. One candidate impurity that could be responsible for this anomalous activity was lithium nitride. Reactions were conducted and it was seen that lithium nitride was very active in the production of ammonia. Subsequent investigations showed that the generation of ammonia probably originates from the direct decomposition of lithium amide

Molybdenum nitrides: structural and reactivity studies

This thesis describes the preparation, structure and activity of a range of binary, ternary and quaternary molybdenum nitrides. It has been shown that all of the samples analysed can be formed through the reaction of the respective molybdate precursor with either ammonia or 3:1 H2/N2 gas mixture. The structures of the nitrides have been studied in detail. These structural findings were then linked to the activity potential of the materials to act as stores of activated nitrogen. The main body of work focused on the ternary molybdenum nitrides of cobalt, iron and nickel with a view to understanding their differences and similarities. Full structural analysis was performed using powder X-ray diffraction (PXRD) and neutron diffraction (PND). The activity of the nitrides was examined by reaction with 3:1 H2/N2 and with 3:1 H2/Ar at various temperatures. Particular attention was paid to the reactivity of lattice nitrogen. The cobalt molybdenum nitride was shown to be special case in this regard where the nitrogen is mobile and relocates within the lattice to a different crystallographic site. This mobility and relocation is concomitant with the loss of 50% of the lattice nitrogen from the system resulting in a phase change from Co3Mo3N to the unprecedented Co6Mo6N phase. The physical and chemical properties of this novel phase have been fully characterised and studied. Interestingly, the isostructual Fe3Mo3N behaves differently and the nitrogen remains fixed and the structure and stoichiometry constant throughout the testing procedure. Further studies of the ternary molybdenum nitrides extended to nickel molybdenum nitride, which was shown to be the least active when tested under both gas mixtures, and analogously to the iron molybdenum nitride the nitrogen is fixed within the β-Mn structured nitride. Further investigations were undertaken, resulting in the successful formation of a series of quaternary nitrides (Fe3-xCoxMo3N). These materials show properties similar to the Co-Mo-N system when the material is cobalt rich and behave similarly to the Fe-Mo-N system when iron rich

Intraindividual Variability in Reaction Time Predicts Cognitive Outcomes 5 Years Later

Objective: Building on results suggesting that intraindividual variability in reaction time (inconsistency) is highly sensitive to even subtle changes in cognitive ability, this study addressed the capacity of inconsistency to predict change in cognitiv

Integrated charging of EVs using existing LVDC light rail infrastructure : a case study

This paper outlines an approach to integrating electric vehicle (EV) charging systems to existing low voltage direct current (LVDC) public electrical transport infrastructure. Existing utility networks face challenges of accommodating a multitude of new connections associated with the adoption of EV charging infrastructure but when present, electrical light rail or tram networks represent a good opportunity to provide fast construction and less disruptive city centre charging implementation. Light rail network operation requires immediate power capacity to be available from any point on the network but if this margin were to be relaxed it opens up opportunities for sharing the available capacity with EV charging systems. This paper presents an electrical capacity assessment based on four separate charging control strategies applied to the public tram system in the City of Edinburgh, Scotland. The results of these studies, earthing and wider system protection requirements are considered and preliminary findings made

Optimal Brain MRI Protocol for New Neurological Complaint

Background/Purpose Patients with neurologic complaints are imaged with MRI protocols that may include many pulse sequences. It has not been documented which sequences are essential. We assessed the diagnostic accuracy of a limited number of sequences in patients with new neurologic complaints. Methods: 996 consecutive brain MRI studies from patients with new neurological complaints were divided into 2 groups. In group 1, reviewers used a 3-sequence set that included sagittal T1-weighted, axial T2-weighted fluid-attenuated inversion recovery, and axial diffusion-weighted images. Subsequently, another group of studies were reviewed using axial susceptibility-weighted images in addition to the 3 sequences. The reference standard was the study's official report. Discrepancies between the limited sequence review and the reference standard including Level I findings (that may require immediate change in patient management) were identified. Results: There were 84 major findings in 497 studies in group 1 with 21 not identified in the limited sequence evaluations: 12 enhancing lesions and 3 vascular abnormalities identified on MR angiography. The 3-sequence set did not reveal microhemorrhagic foci in 15 of 19 studies. There were 117 major findings in 499 studies in group 2 with 19 not identified on the 4-sequence set: 17 enhancing lesions and 2 vascular lesions identified on angiography. All 87 Level I findings were identified using limited sequence (56 acute infarcts, 16 hemorrhages, and 15 mass lesions). Conclusion: A 4-pulse sequence brain MRI study is sufficient to evaluate patients with a new neurological complaint except when contrast or angiography is indicated

The Massachusetts General Hospital Acute Stroke Imaging Algorithm: An Experience and Evidence Based Approach

The Massachusetts General Hospital Neuroradiology Division employed an experience and evidence based approach to develop a neuroimaging algorithm to best select patients with severe ischemic strokes caused by anterior circulation occlusions (ACOs) for intravenous tissue plasminogen activator and endovascular treatment. Methods found to be of value included the National Institutes of Health Stroke Scale (NIHSS), non-contrast CT, CT angiography (CTA) and diffusion MRI. Perfusion imaging by CT and MRI were found to be unnecessary for safe and effective triage of patients with severe ACOs. An algorithm was adopted that includes: non-contrast CT to identify hemorrhage and large hypodensity followed by CTA to identify the ACO; diffusion MRI to estimate the core infarct; and NIHSS in conjunction with diffusion data to estimate the clinical penumbra

Copy Number Variation of <i>CCL3-</i>like Genes Affects Rate of Progression to Simian-AIDS in Rhesus Macaques (<i>Macaca mulatta</i>)

Variation in genes underlying host immunity can lead to marked differences in susceptibility to HIV infection among humans. Despite heavy reliance on non-human primates as models for HIV/AIDS, little is known about which host factors are shared and which are unique to a given primate lineage. Here, we investigate whether copy number variation (CNV) at CCL3-like genes (CCL3L), a key genetic host factor for HIV/AIDS susceptibility and cell-mediated immune response in humans, is also a determinant of time until onset of simian-AIDS in rhesus macaques. Using a retrospective study of 57 rhesus macaques experimentally infected with SIVmac, we find that CCL3L CNV explains approximately 18% of the variance in time to simian-AIDS (pCCL3L copy number associating with more rapid disease course. We also find that CCL3L copy number varies significantly (p−6) among rhesus subpopulations, with Indian-origin macaques having, on average, half as many CCL3L gene copies as Chinese-origin macaques. Lastly, we confirm that CCL3L shows variable copy number in humans and chimpanzees and report on CCL3L CNV within and among three additional primate species. On the basis of our findings we suggest that (1) the difference in population level copy number may explain previously reported observations of longer post-infection survivorship of Chinese-origin rhesus macaques, (2) stratification by CCL3L copy number in rhesus SIV vaccine trials will increase power and reduce noise due to non-vaccine-related differences in survival, and (3) CCL3L CNV is an ancestral component of the primate immune response and, therefore, copy number variation has not been driven by HIV or SIV per se.</p

Outcome of ATP-based tumor chemosensitivity assay directed chemotherapy in heavily pre-treated recurrent ovarian carcinoma

BACKGROUND: We wished to evaluate the clinical response following ATP-Tumor Chemosensitivity Assay (ATP-TCA) directed salvage chemotherapy in a series of UK patients with advanced ovarian cancer. The results are compared with that of a similar assay used in a different country in terms of evaluability and clinical endpoints. METHODS: From November 1998 to November 2001, 46 patients with pre-treated, advanced ovarian cancer were given a total of 56 courses of chemotherapy based on in-vitro ATP-TCA responses obtained from fresh tumor samples or ascites. Forty-four patients were evaluable for results. Of these, 18 patients had clinically platinum resistant disease (relapse < 6 months after first course of chemotherapy). There was evidence of cisplatin resistance in 31 patients from their first ATP-TCA. Response to treatment was assessed by radiology, clinical assessment and tumor marker level (CA 125). RESULTS: The overall response rate was 59% (33/56) per course of chemotherapy, including 12 complete responses, 21 partial responses, 6 with stable disease, and 15 with progressive disease. Two patients were not evaluable for response having received just one cycle of chemotherapy: if these were excluded the response rate is 61%. Fifteen patients are still alive. Median progression free survival (PFS) was 6.6 months per course of chemotherapy; median overall survival (OAS) for each patient following the start of TCA-directed therapy was 10.4 months (95% confidence interval 7.9-12.8 months). CONCLUSION: The results show similar response rates to previous studies using ATP-TCA directed therapy in recurrent ovarian cancer. The assay shows high evaluability and this study adds weight to the reproducibility of results from different centre

Moderators, Mediators, and Prognostic Indicators of Treatment With Hip Arthroscopy or Physical Therapy for Femoroacetabular Impingement Syndrome: Secondary Analyses From the Australian FASHIoN Trial.

BACKGROUND Although randomized controlled trials comparing hip arthroscopy with physical therapy for the treatment of femoroacetabular impingement (FAI) syndrome have emerged, no studies have investigated potential moderators or mediators of change in hip-related quality of life. PURPOSE To explore potential moderators, mediators, and prognostic indicators of the effect of hip arthroscopy and physical therapy on change in 33-item international Hip Outcome Tool (iHOT-33) score for FAI syndrome. STUDY DESIGN Cohort study; Level of evidence, 2. METHODS Overall, 99 participants were recruited from the clinics of orthopaedic surgeons and randomly allocated to treatment with hip arthroscopy or physical therapy. Change in iHOT-33 score from baseline to 12 months was the dependent outcome for analyses of moderators, mediators, and prognostic indicators. Variables investigated as potential moderators/prognostic indicators were demographic variables, symptom duration, alpha angle, lateral center-edge angle (LCEA), Hip Osteoarthritis MRI Scoring System (HOAMS) for selected magnetic resonance imaging (MRI) features, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) score. Potential mediators investigated were change in chosen bony morphology measures, HOAMS, and dGEMRIC score from baseline to 12 months. For hip arthroscopy, intraoperative procedures performed (femoral ostectomy ± acetabular ostectomy ± labral repair ± ligamentum teres debridement) and quality of surgery graded by a blinded surgical review panel were investigated for potential association with iHOT-33 change. For physical therapy, fidelity to the physical therapy program was investigated for potential association with iHOT-33 change. RESULTS A total of 81 participants were included in the final moderator/prognostic indicator analysis and 85 participants in the final mediator analysis after exclusion of those with missing data. No significant moderators or mediators of change in iHOT-33 score from baseline to 12 months were identified. Patients with smaller baseline LCEA (β = -0.82; P = .034), access to private health care (β = 12.91; P = .013), and worse baseline iHOT-33 score (β = -0.48; P < .001) had greater iHOT-33 improvement from baseline to 12 months, irrespective of treatment allocation, and thus were prognostic indicators of treatment response. Unsatisfactory treatment fidelity was associated with worse treatment response (β = -24.27; P = .013) for physical therapy. The quality of surgery and procedures performed were not associated with iHOT-33 change for hip arthroscopy (P = .460-.665 and P = .096-.824, respectively). CONCLUSION No moderators or mediators of change in hip-related quality of life were identified for treatment of FAI syndrome with hip arthroscopy or physical therapy in these exploratory analyses. Patients who accessed the Australian private health care system, had smaller LCEAs, and had worse baseline iHOT-33 scores, experienced greater iHOT-33 improvement, irrespective of treatment allocation

Skunk River Review September 1989, vol 1 no 1

https://openspace.dmacc.edu/skunkriver/1004/thumbnail.jp