20 research outputs found
Synthesis, characterization and catalytic evaluation of a Ziegler-type model iridium hydrogenation catalyst plus a novel tetrairidium tetrahydride complex
No full text2013 Summer.Includes bibliographical references.Following a critical review of the pertinent literature of Ziegler-type hydrogenation catalysts, the research presented herein is primarily focused on the synthesis, characterization and catalytic properties of a model Ziegler-type hydrogenation catalyst system made from [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3. The studies include: (i) a critical review of the relevant literature, (ii) ranking the activity, lifetime and thermal stability of the resulting Ir(0)n Ziegler nanoparticles; (iii) characterization of the true stabilizer species for Ir(0)n Ziegler nanoparticles as a function of the initial Al/Ir ratio; and (iv) the synthesis and characterization of a novel [Ir(1,5-COD)(μ-H)]4 complex considered as a plausible intermediate en route to Ir(0)n Ziegler nanoparticles. Studies evaluating and ranking the catalytic properties of Ziegler-type catalysts in the test reaction of cyclohexene hydrogenation reveal that the catalyst made with [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3 is a highly catalytically active, long-lived and thermally unusually stable nanoparticle catalyst. The catalytic lifetimes of the Ir(0)n Ziegler nanoparticles are higher than any known Ir(0)n nanoparticles in the extant literature. The nature of the stabilizer species in the Ziegler-type catalyst system made with [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3 at Al/Ir ratios 1-3 is then investigated by comparing 1H, 13C, 27Al NMR and IR data of the catalysts with those of individually-synthesized standards such as AlEt2(O2C8H15), [(n-Bu)4N][AlEt3(O2C8H15)] and [(n-Bu)2Al(µ-OH)]3. The results of the study shows that (i) AlEt2(O2C8H15) (Al/Ir=1, 2 and 3) and (iii) free AlEt3 (Al/Ir=3) are present in the catalyst solution in this model Ziegler-type hydrogenation catalyst system made from [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3. The spectroscopic and catalytic evidence provided in this study helps to rule out the initial hypotheses (iii) that anionic [AlEt3(O2C8H15)]- stabilizer exists and provides DLVO-type, Coulombic-repulsion stabilization. Also ruled out is (iv) that the AlEt3-derived stabilizers are Al-O-Al containing alumoxanes. In a separate study, a novel [Ir(1,5-COD)(μ-H)]4 complex is synthesized and characterized with the goal of (i) obtaining information on formation and stabilization mechanisms of Ziegler-type industrial hydrogenation model catalysts prepared from [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3; and with the goal of (ii) understanding the stabilization efficacies of various Al-based cocatalysts in the absence of any added carboxylate.The synthesis of the previously unavailable [Ir(1,5-COD)(μ-H)]4 complex in 55% recrystallized yield was accomplished starting with commercially available LiBEt3H and [Ir(1,5-COD)(μ-Cl)]2 in the presence of excess 1,5-COD in THF. The resultant [Ir(1,5-COD)(μ-H)]4 was fully characterized by single-crystal XRD, XAFS, ESI-MS, UV-visible, IR, and NMR. In addition to the four main chapters, two appendix chapters (in which Isil K. Hamdemir has significant contributions) are included in the current dissertation due to their relevancy to the research presented herein. The characterization studies showing the presence of Ir~4-15 subnanometer clusters and Ir~40-150 nanoparticles, before and after catalytic hydrogenation, respectively, in the Ziegler-type catalyst system made from [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3 catalyst solution has been published (William M. Alley, Isil K. Hamdemir, Qi Wang, Anatoly Frenkel, Long Li, Judith C. Yang, Laurent D. Menard, Ralph G. Nuzzo, Saim Özkar, Kimberly Johnson, Richard G. Finke, "Iridium Ziegler-Type Hydrogenation Catalysts Made from [(1,5-COD)(μ-O2C8H15)]2 and AlEt3: Spectroscopic and Kinetic Evidence for the Irn Species Present and for Nanoparticles as the Fastest Catalyst"). Additionally, a broad distribution of metal cluster sizes from subnanometer to nanometer scale particles was observed in industrial Ziegler-type hydrogenation catalysts made with Co(neodecanoate)2 or Ni(2-ethylhexanoate)2 plus AlEt3 (William M. Alley, Isil K. Hamdemir, Qi Wang, Anatoly I. Frenkel, Long Li, Judith C. Yang, Laurent D. Menard, Ralph G. Nuzzo, Saim Özkar, Kimberly Johnson, Richard G. Finke, "Industrial Ziegler-type Hydrogenation Catalysts made from Co(neodecanoate)2 or Ni(2-ethylhexanoate)2, and AlEt3: Evidence for Nanoclusters and Sub-Nanocluster or Larger Ziegler-Nanocluster Based Catalysis"). These two studies were published as two chapters in the dissertation of, graduate student co-worker, William M. Alley, a dissertation which acknowledges Isil Kayiran Hamdemir's (I.K.H.) contributions
Lasagne : a static binary translator for weak memory model architectures
No full textFunding: This work was supported by a UK RISE Grant.The emergence of new architectures create a recurring challenge to ensure that existing programs still work on them. Manually porting legacy code is often impractical. Static binary translation (SBT) is a process where a program’s binary is automatically translated from one architecture to another, while preserving their original semantics. However, these SBT tools have limited support to various advanced architectural features. Importantly, they are currently unable to translate concurrent binaries. The main challenge arises from the mismatches of the memory consistency model specified by the different architectures, especially when porting existing binaries to a weak memory model architecture. In this paper, we propose Lasagne, an end-to-end static binary translator with precise translation rules between x86 and Arm concurrency semantics. First, we propose a concurrency model for Lasagne’s intermediate representation (IR) and formally proved mappings between the IR and the two architectures. The memory ordering is preserved by introducing fences in the translated code. Finally, we propose optimizations focused on raising the level of abstraction of memory address calculations and reducing the number offences. Our evaluation shows that Lasagne reduces the number of fences by up to about 65%, with an average reduction of 45.5%, significantly reducing their runtime overhead.Postprin
Comparação de diferentes testes para determinar intubação difícil em pacientes pediátricos
No full textResumoJustificativaAs dificuldades no manejo das vias aéreas são a principal causa de morbidade e mortalidade relacionada à anestesia pediátrica.ObjetivoAvaliar o valor do teste modificado de Mallampati, teste da mordida do lábio superior, distância tireomentoniana e relação altura‐distância tireomentoniana para prever intubação difícil em pacientes pediátricos.ProjetoAnálise prospectiva.Mensurações e resultadosDados coletados de 250 pacientes pediátricos, com idades entre 5 e 11 anos, submetidos à intubação traqueal. A classificação de Cormack e Lehane foi usada para avaliar laringoscopia difícil. Os valores de sensibilidade, especificidade, preditivo positivo e AUC para cada teste foram registrados.ResultadosA sensibilidade e especificidade do teste modificado de Mallampati foram 76,92% e 95,54%, enquanto para o ULBT foram 69,23% e 97,32%. O ponto de corte ideal para a relação altura‐distância tireomentoniana e distância tireomentoniana para prever laringoscopia difícil foi 23,5 (sensibilidade, 57,69%; especificidade, 86,61%) e 5,5cm (sensibilidade, 61,54%; especificidade, 99,11%). O teste de Mallampati modificado foi o mais sensível dos testes. A relação entre altura‐distância tireomentoniana foi o teste menos sensível.ConclusãoEsses resultados sugerem que os testes de Mallampati modificado e da mordida do lábio superior podem ser úteis em pacientes pediátricos para a previsão de intubação difícil.AbstractBackgroundThe difficulties with airway management is the main reason for pediatric anesthesia‐related morbidity and mortality.ObjectiveTo assess the value of modified Mallampati test, Upper‐Lip‐Bite test, thyromental distance and the ratio of height to thyromental distance to predict difficult intubation in pediatric patients.DesignProspective analysis.Measurements and resultsData were collected from 5 to 11 years old 250 pediatric patients requiring tracheal intubation. The Cormack and Lehane classification was used to evaluate difficult laryngoscopy. Sensitivity, specificity, positive predictive value and AUC values for each test were measured.ResultsThe sensitivity and specificity of modified Mallampati test were 76.92% and 95.54%, while those for ULBT were 69.23% and 97.32%. The optimal cutoff point for the ratio of height to thyromental distance and thyromental distance for predicting difficult laryngoscopy was 23.5 (sensitivity, 57.69%; specificity, 86.61%) and 5.5cm (sensitivity, 61.54%; specificity, 99.11%). The modified Mallampati was the most sensitive of the tests. The ratio of height to thyromental distance was the least sensitive test.ConclusionThese results suggested that the modified Mallampati and Upper‐Lip‐Bite tests may be useful in pediatric patients for predicting difficult intubation
Postoperative Analgesic Effects of Wound Infiltration With Tramadol and Levobupivacaine in Lumbar Disk Surgeries
No full textBackground: Wound infiltration with local anesthetics may improve postoperative analgesia. Tramadol has been shown to have effects similar to those of local anesthetics. The purpose of this study was to investigate the effects of wound infiltration with levobupivacaine and tramadol on postoperative analgesia for lumbar discectomies
Impacto do anestesiologista em treinamento sobre as pressões do manguito de máscara laríngea e incidência de eventos adversos
No full textResumoObjetivoPlanejamos avaliar as pressões do manguito de máscara laríngea (PMML) inflado por profissionais da área de anestesiologia com tempos de serviço variados, sem o uso de manômetro.Métodos180 pacientes agendados para cirurgia de curta duração com máscara laríngea foram incluídos no estudo. Cinco especialistas em anestesia (Grupo E), 10 residentes (Grupo R) e seis técnicos (Grupo T) inflaram os manguitos das máscaras laríngeas; subsequentemente, as PMML foram medidas com manômetro de pressão. Os participantes repetiram essa prática em pelo menos cinco casos diferentes. As PMML superiores a 60cm H2O na colocação inicial ou no intraoperatório foram ajustadas para valores normais. Os pacientes foram questionados sobre a presença de dor de garganta no período pós‐operatório. Os grupos foram comparados quanto à média das PMML e experiência profissional.ResultadosAo inserirem a ML, as pressões do manguito dentro da faixa normal foram determinadas em 26 (14,4%) casos. As médias das PMML após a inserção da ML pelos grupos E, R e T foram 101,2±14,0, 104,3±20,5cm e 105,2±18,4cm H2O, respectivamente, (p>0,05). A média dos valores das PMML em todos os períodos de mensuração entre os grupos estava acima do limite normal (60cm H2O). Quando os grupos foram comparados quanto às PMML, nenhuma diferença foi encontrada entre os valores das pressões. A experiência profissional era de 14,2±3,9; 3,3±1,1 e 6,6±3,8 anos para especialistas, residentes e técnicos, respectivamente, e os valores das pressões mensuradas não foram diferentes em relação à experiência profissional. Sete pacientes (3,9%) apresentaram dor de garganta durante a entrevista realizada na 24a hora.ConclusãoLevando‐se em consideração uma possibilidade menor de ajuste da pressão do manguito da máscara laríngea (PMML) e da ineficácia da experiência profissional para a obtenção de valores normais das pressões, é adequado que todos os profissionais de anestesia ajustem as PMML com manômetro.AbstractObjectiveWe have planned to evaluate the laryngeal mask cuff pressures (LMcp) inflated by anesthesia workers of several seniority, without using manometer.Methods180 patients scheduled to have short duration surgery with laryngeal mask were included in the study. Five anesthesia specialists (Group S), 10 residents (Group R) and 6 technicians (Group T) inflated the LMc; thereafter LMcp were measured with pressure manometer. Participants have repeated this practice in at least five different cases. LMcp higher than 60cm H2O at the initial placement or intraoperative period were adjusted to normal range. Sore throat was questioned postoperatively. Groups were compared in terms of mean LMcp and occupational experience.ResultsAt the settlement of LM, LMcp pressures within the normal range were determined in 26 (14.4%) cases. Mean LMcp after LM placement in Group S, R and T were 101.2±14.0, 104.3±20.5cm H2O and 105.2±18.4cm H2O respectively (p>0.05). Mean LMcp values in all measurement time periods within the groups were above the normal limit (60cm H2O). When groups were compared in terms of LMcp, no difference has been found among pressure values. Occupational experience was 14.2±3.9; 3.3±1.1 and 6.6±3.8 years for specialists, residents and technicians respectively and measured pressure values were not different in regard of occupational experience. Seven (3.9%) patients had sore throat at the 24th hour interview.ConclusionConsidering lower possibility of normal adjustment of LMcp and ineffectiveness of occupational experience to obtain normal pressure values, it is suitable that all anesthesia practitioners should adjust LMcp with manometer
Influence of Menstrual Cycle on P Wave Dispersion
No full textFemale gender is an independent risk factor for some types of arrhythmias. We sought to determine whether the menstrual cycle affects P wave dispersion, which is a predictor of atrial fibrillation. The study population consisted of 59 women in follicular phase (mean age, 29.3 +/- 7.7 years) (group F) and 53 women in luteal phase (mean age, 28.1 +/- 6.8 years) (group L). The ECGs of 35 patients (mean age, 26.4 +/- 4.5) were obtained in both follicular and luteal phase. Both groups underwent a standard 12-lead surface electrocardiogram recorded at 50 mm/s. Maximal (Pmax) and minimal P wave durations (Pmin) were measured. P wave dispersion (PD) was defined as the difference between Pmax and Pmin. PD was significantly higher in group L than group F (46.6 +/- 18.5 versus 40.1 +/- 12.7; P < 0.05). Pmin was significantly lower in group L than group F (51.6 +/- 12.1 versus 59.1 +/- 12.1; P = 0.002). When we compared ECGs in different phases of the 35 patients, PD was significantly higher in luteal phase than follicular phase (53.2 +/- 12.3 versus 42.8 +/- 10.2; P < 0.05). Pmin was significantly lower in luteal phase than follicular phase (47.6 +/- 6.6 versus 56 +/- 10.1; P = 0.05). We detected a significant correlation between the day of the menses and PD (r = 0.27; P < 0.05). PD was increased in luteal phase compared to follicular phase, and this difference was more prominent as the days of the cycle progressed. (Int Heart J 2011; 52: 23-26
A rare cause of fetal neck mass: Cervical lymphangioma
No full textIntroduction: Fetal neck masses are rare. In general, cystic hygroma is the most frequent form of fetal neck masses. It is essential to differentiate between different pathologies since this will affect prenatal counselling, antenatal and postnatal management. We aimed to present a case of cervical lymphangioma who was referred to our perinatology outpatient clinic with a diagnosis of an occipital encephalocele
Pseudocholinesterase levels in patients under electroconvulsive therapy
No full textObjectives: In this study, we aimed to retrospectively assess the correlation of pseudocholinesterase (PChE) levels with age, gender, body weight and diagnosed psychiatric diseases in electroconvulsive therapy (ECT) cases
Clinical presentations and diagnostic work-up in sarcoidosis: a series of Turkish cases (clinics and diagnosis of sarcoidosis).
No full textUS Presidents as Foreign Policy Actors: George W. Bush and Barack Obama
No full textOvaj rad se bavi usporedbom vanjskih politika predsjednika Georgea W. Busha i predsjednika Baracka Obame. Njihove vanjske politike se u radu uspoređuju na temelju tri ključne točke: unilateralizam nasuprot multilateralizmu u vanjskoj politici prema UN-u i NATO-u i na temelju njihove sklonosti prema korištenju sile u vanjskoj politici. U radu se prvo opisuje institucionalni okvir američkog vanjskopolitičkog odlučivanja kako bi se prikazala uloga predsjednika u tom procesu, za koju se tvrdi da je veća i bitnija u odnosu na ulogu ostalih aktera. S obzirom na to, može se govoriti o vanjskoj politici određenog američkog predsjednika. Na temelju usporedbe vanjskih politika Busha i Obame, zaključuje se da je Obama napravio zaokret u odnosu na Busha jer je za razliku od njega prigrlio multilateralizam. Ipak, ne može se reći da je bio manje sklon upotrebi sile što je vidljivo u njegovoj intervenciji u Libiju i upotrebi bespilotnih letjelica u borbi protiv ISIL-a. Glavna razlika je u načinu na koji su koristili silu, pri čemu je Bush djelovao unilateralno uz pomoć koalicije voljnih, dok je Obama naglašavao multilateralno djelovanje.In this paper, the author compares President George W. Bush's foreign policy with President Barack Obama's foreign policy. Their foreign policies are compared on three key points: unilateralism versus multilateralism in their foreign policies towards the UN and NATO, and their tendency towards using force. This paper first describes the institutional frame of American foreign policy-making process with the purpose of showing the role of the president in that process, which is claimed to be bigger and more important than the role of other actors. Having this in mind, one may refer to the American foreign policy as a certain president's foreign policy. Based on the comparison of Bush's and Obama's foreign policies, it can be concluded that President Obama made a turn when compared to President Bush because he embraced multilateralism. However, it cannot be said that President Obama was less prone to using force because of his intervention in Libya and use of drones against the ISIS. The main difference between them is the way in which they were using force. While Bush was acting unilaterally, Obama embraced multilateral action
