ABSTRACT Cusped-field Hall thrusters (CFHT) have significant potential for use in many space missions due to their simplicity, long life and high efficiency. CFHT-27, designed and developed at the Bogazici University Space Technologies Laboratory (BUSTLab), is a prototype CFHT with a 27-mm diameter discharge channel. CFHT-27 utilizes samarium-cobalt (SmCo) permanent magnets. The thrust and efficiency of a cusped-field thruster is closely related to its size and design parameters. In this study, in order to understand the relationships between the design parameters and the thruster performance, the performance tests of the CFHT-27 are carried out for a given magnetic field topology. The thruster was operated at discharge voltages ranging from 250 to 500V with argon propellant with up to 3,000 s of specific impulse. The measurements show that CFHT-27 can achieve thrust values from 1 to 46 mN. Thus, this thruster can be used for a wide range of thrust values allowing throttle capabilities for different missions.

ABSTRACT Vacuum chambers providing a low pressure environment similar to the vacuum environment in low earth orbit have been used for the testing of plasma thrusters. A significant proportion of research on the effects of vacuum facility on plasma thrusters has focused on the effects of background pressure and plume expansion; however, the electrical interaction of the conductive chamber walls with the plasma thrusters needs to be explored further. In this study, the operation of a prototype Hall thruster, HK40, was investigated to understand the effects of wiring configuration of the thruster-cathode-chamber system. During the tests, the thruster was operated in two different grounding configurations. A resistance analogy regarding the changes in the electrical potentials and measured currents was introduced. The calculated thrust and efficiency values of the two configurations were compared. This study shows that the current extracted from the emitter surface of the cathode, along with the cathode-to-ground voltage can be used to estimate the thrust and thruster efficiency. In addition, the theoretical predictions were compared with the values based on the measurements made with an in-house-built inverted pendulum type thrust stand. The presented results show that the thrust and efficiency values are predicted with 3.4% and 8.3% uncertainty, respectively.

Abstract Background Comparative data on the performance of cardiovascular risk scoring systems (CRSSs) in patients with severe coronary artery disease (CAD) are lacking. Objectives To compare different CRSSs regarding their ability to discriminate patients with severe CAD. Method A total of 414 patients (297 men; 61.3±12.3 years of age) undergoing coronary angiography were enrolled and evaluated for major risk factors. Cardiovascular risk and risk category were defined for each patient using the Framingham, Systemic Coronary Risk Evaluation (SCORE), and Pooled Cohort Risk Assessment Equation (PCRAE) tools. Severe CAD was defined as ≥ 50% stenosis in at least one major coronary artery and/or previous coronary stenting or coronary artery bypass grafting. A p < 0.05 was considered statistically significant. Results Severe CAD was identified in 271 (65.4%) patients. The ROC curves of the 3 CRSSs for predicting severe CAD were compared and showed no significant difference: the area under the ROC curve was 0.727, 0.694, and 0.717 for the Framingham, SCORE, and PCRAE tools, respectively (p > 0.05). However, when individual patients were classified as having low, intermediate, or high cardiovascular risk, the rate of patients in the high-risk group was significantly different between the PCRAE, Framingham, and SCORE tools (73.4%, 27.5%, and 37.9%, respectively; p < 0.001). Discussion PCRAE had higher positive and negative predictive values for detecting severe CAD in high-risk patients than the Framingham and SCORE tools. Conclusion We can speculate that currently used CRSSs are not sufficient, and new scoring systems are needed. In addition, other risk factors, such as serum creatinine, should be considered in future CRSSs. Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0

Resumo Fundamento: Até o momento, diversos escores de risco baseados em pacientes foram estabelecidos para a predição de mortalidade em pacientes com infarto do miocárdio com supradesnivelamento do segmento ST (IAMCSST). O escore de Gensini foi originalmente desenvolvido para quantificar a gravidade de doença arterial coronariana (DAC). Objetivos: Avaliar a associação entre a gravidade de DAC avaliada pelo escore de Gensini e mortalidade intra-hospitalar em pacientes com IAMCSST submetidos à intervenção coronária percutânea primária (ICP-P). Métodos: Foram incluídos 539 pacientes com IAMCSST, submetidos à ICP-P dentro das primeiras 12 horas do início dos sintomas. A gravidade da DAC foi expressa como a soma do escore de Gensini para cada lesão. Variáveis demográficas, anamnese e características clínicas dos pacientes, bem como eventos hospitalares significativos, foram obtidos de relatórios médicos. Resultados: Dos 539 pacientes, 416 (77,2%) eram do sexo masculino, e a idade média era 59,14 ± 12,68 anos. A taxa de mortalidade intra-hospitalar foi de 5,4% (29 pacientes, 16 homens). A taxa de mortalidade foi de 10,5% em pacientes do sexo feminino e 3,8% em pacientes do sexo masculino (P = 0,004). Os escores de Gensini médios mostraram-se significativamente diferentes na comparação entre pacientes que sobreviveram (54,54 ± 26,34) e aqueles que foram a óbito (80,17 ± 26,51) (P = 0,001). O modelo de análise multivariada de regressão de Cox de risco proporcional revelou que o escore de Gensini (P = 0,037), o sexo feminino (P = 0,039), níveis séricos de ureia (P = 0,041), níveis de ácido úrico (P = 0,008) e FEVE (P = 0,001) estavam independentemente associados à mortalidade intra-hospitalar em pacientes com IAMCSST submetidos à ICP-P. Conclusões: O escore de Gensini está independentemente associado à mortalidade intra-hospitalar em pacientes com IAMCSST tratados com ICP-P. Portanto, o escore pode ter um papel importante na estratificação de risco de pacientes com IAMCSST.

Abstract Background: To date, several validated patient-based risk scores have been established to predict mortality and morbidity in patients presenting with ST-segment elevation myocardial infarction (STEMI). The Gensini score was originally developed to quantify the severity of coronary artery disease (CAD). Objectives: We intend to assess the association between severity of CAD assessed by Gensini score and in-hospital mortality in patients with STEMI undergoing primary percutaneous coronary intervention (P-PCI). Methods: A total of 539 patients presenting with acute STEMI, who underwent P-PCI within the first 12 hours from the onset of symptoms, were included. The severity of CAD was expressed as the sum of the Gensini scores for each lesion. Patients' demographic variables, medical histories and clinical features, as well as in hospital major adverse events were obtained from the medical reports. Results: Of these 539 patients, 416 (77.2%) were male and mean age was 59.14 ± 12.68 years. In-hospital mortality rate was 5.4% (29 patients; 16 men). Mortality rate was 10.5% in female patients and 3.8% in males (P = 0.004). Mean Gensini scores were significantly different in the comparison between patients who survived (54.54 ± 26.34) and those who died (80.17 ± 26.51) (P = 0.001). The multivariable Cox proportional hazards regression analysis model revealed that the Gensini score (P = 0.037), female gender (P = 0.039), serum urea levels (P = 0.041), uric acid levels (P = 0.008) and LVEF (P = 0.001) were independently associated with in-hospital mortality in patients with STEMI undergoing P-PCI. Conclusion: The Gensini score is independently associated with in-hospital mortality in STEMI patients treated with P-PCI. Therefore, it might play an important role in risk stratification of STEMI patients.

Fundamento: A relação neutrófilos/linfócitos (N/L) tem sido descrita como boa preditora de eventos cardiovasculares adversos futuros em pacientes com infarto agudo do miocárdio com elevação do segmento ST (IAMEST). Mudanças na porção terminal do complexo QRS também têm sido associadas a eventos adversos após IAMEST. Objetivo: Investigar a associação entre o grau de isquemia no ECG e a relação N/L em pacientes com IAMEST para determinar fatores de risco convencionais adicionais na estratificação precoce de risco. Métodos: Pacientes com IAMEST foram investigados. O grau de isquemia foi analisado a partir do ECG obtido à admissão. A contagem de leucócitos e seus subtipos foi realizada a partir de hemograma automatizado. De acordo com o grau de isquemia presente no ECG de admissão, os pacientes foram classificados em dois grupos, isquemia grau 2 (IG2) e isquemia grau 3 (IG3). Resultados: Pacientes com IG3 apresentaram valores médios significativamente menores de fração de ejeção do ventrículo esquerdo do que os pacientes com IG2 (44,58 ± 7,23 versus 48,44 ± 7,61; p = 0,001). Como esperado, a taxa de mortalidade intra-hospitalar aumentou proporcionalmente com o aumento no grau de isquemia (p = 0,036). Houve diferenças significativas nas porcentagens de linfócitos (p = 0,010) e de neutrófilos (p = 0,004) e, portanto, a relação N/L diferiu significativamente entre pacientes com IG2 e IG3 (p < 0,001). À análise de regressão logística multivariada, apenas a relação N/L emergiu como variável independente com efeito significativo sobre o grau de isquemia no ECG (odds ratio = 1,254; intervalo de confiança de 95% 1,120-1,403; p < 0,001). Conclusão: Nós encontramos uma associação entre IG3 e relação N/L aumentada em pacientes com IAMEST. Acreditamos que esta associação possa oferecer um valor prognóstico adicional para estratificação de risco em pacientes com IAMEST quando usado em combinação com escores de risco padronizados.

Background: Neutrophil-to-lymphocyte ratio (NLR) has been found to be a good predictor of future adverse cardiovascular outcomes in patients with ST-segment elevation myocardial infarction (STEMI). Changes in the QRS terminal portion have also been associated with adverse outcomes following STEMI. Objective: To investigate the relationship between ECG ischemia grade and NLR in patients presenting with STEMI, in order to determine additional conventional risk factors for early risk stratification. Methods: Patients with STEMI were investigated. The grade of ischemia was analyzed from the ECG performed on admission. White blood cells and subtypes were measured as part of the automated complete blood count (CBC) analysis. Patients were classified into two groups according to the ischemia grade presented on the admission ECG, as grade 2 ischemia (G2I) and grade 3 ischemia (G3I). Results: Patients with G3I had significantly lower mean left ventricular ejection fraction than those in G2I (44.58 ± 7.23 vs. 48.44 ± 7.61, p = 0.001). As expected, in-hospital mortality rate increased proportionally with the increase in ischemia grade (p = 0.036). There were significant differences in percentage of lymphocytes (p = 0.010) and percentage of neutrophils (p = 0.004), and therefore, NLR was significantly different between G2I and G3I patients (p < 0.001). Multivariate logistic regression analysis revealed that only NLR was the independent variable with a significant effect on ECG ischemia grade (odds ratio = 1.254, 95% confidence interval 1.120–1.403, p < 0.001). Conclusion: We found an association between G3I and elevated NLR in patients with STEMI. We believe that such an association might provide an additional prognostic value for risk stratification in patients with STEMI when combined with standardized risk scores.

The synthesis and molecular structures of six new mono- and trinuclear complexes [M¹L2(M²{Phen)}2J(ClO4)2 [phen = 1,10-phenanthroline, H2L = dioxime ligand, M¹, M² =Ni(II) and Cu(II)] of the ligand, 4-(4-methylphenylamino) biphenylglyoxime are reported. Structural assignments are supported by a combination of FT-IR, elemental analyses, ICP-OES, magnetic susceptibility and molar conductivity studies. Furthermore these complexes were each tested for their ability to catalyze the oxidation of catechol substrates to quinone with dioxygen at 25ºC and disproportionation of hydrogen peroxide in the presence of the added base imidazole. The catalytic results indicated that the heterotrinuclear Cu(II)Ni(II)Cu(II) complex (5) shows greater catecholase activity. On the other hand the trinuclear complexes display efficiency in disproportion reactions of hydrogen peroxide producing water and dioxygen in catalase-like activity and homotrinuclear Cu(II) (6) complex is more active towards catalytic decomposition of hydrogen peroxide. The interaction between these compounds with DNA has also been investigated by agarose gel electrophoresis, the trinuclear copper(II) complexes (5, 6) with H2O2 as a cooxidant exhibited the strongest cleaving activity.

OBJECTIVE: This retrospective study aimed to investigate the relationship between admission levels of serum y-glutamyltransferase and poor myocardial perfusion after primary percutaneous coronary intervention in patients with acute myocardial infarction. INTRODUCTION: Reperfusion injury caused by free radical release and increased oxidative stress is responsible for the pathophysiology of the no-reflow phenomenon in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Serum ϒ-glutamyltransferase is an established marker of increased oxidative stress. METHODS: The study population consisted of 80 patients (64 men and 16 women, mean age = 67.5 + 6.6 years) with thrombolysis in myocardial infarction 0/1 flow pre-procedurally. The patients were divided into two groups according to thrombolysis in myocardial perfusion grades that were assessed immediately following primary percutaneous coronary intervention. The two groups (group 1 and group 2) each consisted of 40 patients with thrombolysis in myocardial perfusion grades 0-1 and thrombolysis in myocardial perfusion grades 2-3, respectively. RESULTS: Admission pain to balloon time, ϒ-glutamyltransferase and creatine kinase-MB isoenzyme levels of group 1 patients were significantly higher than those of group 2 patients. Pain to balloon time, ϒ-glutamyltransferase, peak creatine kinase-MB isoenzyme, low left ventricular ejection fraction and poor pre-procedural thrombolysis in myocardial infarction grade were significantly associated with poor myocardial perfusion by univariate analysis. However, only pain to balloon time and ϒ-glutamyltransferase levels showed a significant independent association with poor myocardial perfusion by backward logistic regression analysis. Adjusted odds ratios were calculated as 4.92 for pain to balloon time and 1.13 for ϒ-glutamyltransferase. CONCLUSION: High admission ϒ-glutamyltransferase levels are associated with poor myocardial perfusion in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention, particularly in patients with prolonged pain to balloon time.