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Assisted reproduction is a key aspect of modern animal breeding, providing valuable assistance in improving breeding programs. In this field, the administration of exogenous hormones, such as follicle-stimulating hormone (FSH), plays a crucial role in the induction of multiple ovulations. However, commercial FSH used in veterinary practice has been derived primarily from pituitary glands, obtained mostly from pigs for nearly four decades. Although these hormones have contributed significantly to the advancement of assisted reproductive techniques, they have certain limitations that warrant further improvements. These limitations include contamination with luteinizing hormone (LH), the potential risk of pathogen contamination, the potential to trigger an immune response in non-pig species, and the short half-life in circulation, requiring the implementation of complex 8-dose superovulation schedules. Our research team has developed and characterized a new variant of bovine follicle-stimulating hormone (bscrFSH) to address these limitations. The new hormone is produced recombinantly in CHO cell cultures, with a specific productivity of about 30 pg/cell/day. The bscrFSH can be purified to a high purity of 97 % using a single step of immobilized metal affinity chromatography (IMAC). N-glycan analysis of bscrFSH showed that approximately 74 % of the glycans corresponded to charged structures, including mono-, di-, tri-, and tetra-sialylated glycans. Superovulation trials conducted in cattle revealed that bscrFSH, administered at a total dose of about 0.5 µg per kg of body weight, using a decrescent schedule of 4 doses with 24-h intervals, resulted in an average yield of 8-12 transferable embryos per animal. Further research is required; however, the preliminary findings indicate that bscrFSH, currently packaged under the provisional brand name of Cebitropin B, holds potential as a commercial product for assisted reproduction in ruminants.
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Hormônio Foliculoestimulante , Animais , Bovinos , Hormônio Foliculoestimulante/farmacologia , Hormônio Foliculoestimulante/administração & dosagem , Feminino , Células CHO , Cricetulus , Proteínas Recombinantes , Superovulação/efeitos dos fármacosRESUMO
Over the past three decades, the synthesis of new ionic liquids (ILs) and the expansion of their use in newer applications have grown exponentially. From the beginning of this vertiginous period, it was known that many of them were hygroscopic, which in some cases limited their use or altered the value of their measured physical properties with all the problems that this entails. In an earlier article, we addressed the hygroscopic grade achieved by the ILs 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylpyridinium ethyl sulfate, 1-ethyl-3-methylimidazolium tosylate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-dodecyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-1-methylpiperidinium bis(trifluoromethyl sulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethyl sulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl)imide, and methyl trioctyl ammonium bis(trifluoromethyl sulfonyl)imide. The objective was to determine the influence of the chemical nature of the compounds, exposed surface area, sample volume, agitation, and temperature. For this purpose, we exposed the samples to abrupt increases in relative humidity from 15 to 100% for days in an atmosphere chamber and then proceeded with the reverse process in a gentle manner. The results show that the sorption of water from the atmosphere depends on the nature of the IL, especially the anion, with the chloride anion being of particular importance (chloride â« alkyl sulfates~bromide > tosylate â« tetrafluoroborate). It has also been proven for the EMIM-ES and EMIM-BF4 samples that the mechanism of moisture capture is both absorption and adsorption, and that the smaller the exposed surface area, the higher the ratio of the mass of water per unit area.
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Ânions , Cátions , Líquidos Iônicos , Líquidos Iônicos/química , Ânions/química , Cátions/química , Imidazóis/química , Molhabilidade , Água/químicaRESUMO
In this work, we deepen in the characterization of two protic ionic liquids (PILs), ethylammonium nitrate (EAN) and propylammonium nitrate (PAN). With this aim, we determined the influence of inorganic nitrate salts addition on their physical properties and their electrochemical potential window (EPW). Thus, experimental measurements of electrical conductivity, density, viscosity, refractive index and surface tension of mixtures of {EAN or PAN + LiNO3, Ca(NO3)2, Mg(NO3)2 or Al(NO3)3} at a temperature range between 5 and 95 °C are presented first, except for the last two properties which were measured at 25 °C. In the second part, the corresponding EPWs were determined at 25 °C by linear sweep voltammetry using three different electrochemical cells. Effect of the salt addition was associated mainly with the metal cation characteristics, so, generally, LiNO3 showed the lower influence, followed by Ca(NO3)2, Mg(NO3)2 or Al(NO3)3. The results obtained for the EAN + LiNO3 mixtures, along with those from a previous work, allowed us to develop novel predictive equations for most of the presented physical properties as functions of the lithium salt concentration, the temperature and the water content. Electrochemical results showed that a general order of EPW can be established for both PILs, although exceptions related to measurement conditions and the properties of the mixtures were found.
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Líquidos Iônicos , Nitratos , Nitratos/química , Sais , Líquidos Iônicos/química , Compostos de Amônio Quaternário/químicaRESUMO
OBJECTIVE: To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG. MATERIAL AND METHODS: A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed. STATISTICAL ANALYSIS: Survival analysis was performed for time-to-event data to assess patency. RESULTS: Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in group B and 94.5% and 91% respectively in group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% y 15.7% respectively. Group B: 100%, 85.9%, 76,4% (p < 0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% y 31.3% respectively. Group B 100%, 95.3%, 95.2% (p < 0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 IC 95% 1.146-6.216, p = 0.010). CONCLUSION: A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.
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Derivação Arteriovenosa Cirúrgica , Implante de Prótese Vascular , Trombose , Humanos , Derivação Arteriovenosa Cirúrgica/efeitos adversos , Oclusão de Enxerto Vascular/etiologia , Oclusão de Enxerto Vascular/cirurgia , Grau de Desobstrução Vascular , Constrição Patológica/cirurgia , Constrição Patológica/complicações , Implante de Prótese Vascular/efeitos adversos , Stents/efeitos adversos , Estudos Retrospectivos , Trombectomia/efeitos adversos , Resultado do Tratamento , Diálise Renal/efeitos adversos , Trombose/etiologia , PolitetrafluoretilenoRESUMO
OBJECTIVE: To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG. MATERIAL AND METHODS: A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed. STATISTICAL ANALYSIS: Survival analysis was performed for time-to-event data to assess patency. RESULTS: Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in Group B and 94.5% and 91% respectively in Group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% and 15.7% respectively. Group B: 100%, 85.9%, 76.4% (p<0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% and 31.3% respectively. Group B 100%, 95.3%, 95.2% (p<0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 95% CI 1.146-6.216, p=0.010). CONCLUSION: A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.
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This paper presents a comprehensive study of two alkylammonium nitrate ionic liquids. As part of this family of materials, mainly ethylammonium nitrate (EAN) and also propylammonium nitrate (PAN) have attracted a great deal of attention during the last decades due to their potential applications in many fields. Although there have been numerous publications focused on the measurement of their physical properties, a great dispersion can be observed in the results obtained for the same magnitude. One of the critical points to be taken into account in their physical characterization is their water content. Thus, the main objective of this work was to determine the degree of influence of the presence of small quantities of water in EAN and PAN on the measurement of density, viscosity, electrical conductivity, refractive index and surface tension. For this purpose, the first three properties were determined in samples of EAN and PAN with water contents below 30,000 ppm in a wide range of temperatures, between 5 and 95 °C, while the last two were obtained at 25 °C. As a result of this study, it has been concluded that the presence of water is critical in those physical properties that involve mass or charge transport processes, resulting in the finding that the absolute value of the average percentage change in both viscosity and electrical conductivity is above 40%. Meanwhile, refractive index (≤0.3%), density (≤0.5%) and surface tension (≤2%) present much less significant changes.
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Líquidos Iônicos/química , Nitratos/química , Compostos de Amônio Quaternário/química , Água/químicaRESUMO
Aortic dissection is exceptional in children. When they are affected, many clinical conditions as Marfan syndrome or Ehlers-Danlos syndrome are usually involved, but up to 22% have no associated background. Its high morbidity and low incidence in this age group require a high level of suspicion in children without predisposing factors when the presentation is atypical, to avoid the severe consequences of the delay of their diagnosis. In this article we describe the dissection and aortic rupture in a 12-year-old child without relevant medical history, and the open repair that was performed as treatment.
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Aneurisma da Aorta Torácica/cirurgia , Dissecção Aórtica/cirurgia , Ruptura Aórtica/cirurgia , Implante de Prótese Vascular , Dissecção Aórtica/diagnóstico por imagem , Dissecção Aórtica/etiologia , Aneurisma da Aorta Torácica/diagnóstico por imagem , Aneurisma da Aorta Torácica/etiologia , Ruptura Aórtica/diagnóstico por imagem , Ruptura Aórtica/etiologia , Prótese Vascular , Implante de Prótese Vascular/instrumentação , Criança , Humanos , Masculino , Fatores de Risco , Resultado do TratamentoRESUMO
BACKGROUND: The objective of the study was to evaluate the impact of initial aneurysmal sac reduction after endovascular aneurysm repair on the evolution of aneurysmal sac over follow-up. METHODS: A retrospective cohort study was made of patients subjected to elective treatment between January 2005 and December 2014, with a minimum follow-up of 18 months. An analysis was made of the evolution of the aneurysmal sac according to its condition one year after surgery, defining of two groups: A (sac reduction) and B (stable sac). Follow-up by computed tomography (CT) angiography was made after one month and then every 6 months or annually, depending on the presence of endoleak. RESULTS: A total of 128 patients were included. Fifty-one patients (39.8%) showed a significant decrease in diameter during the first year (group A), whereas 77 patients (60.2%) showed no initial decrease (group B). Preoperative CT angiography showed the patients in group A to have larger aneurysms (63.5 mm vs. 59.25; P = 0.048), a greater presence of posterior thrombus (68.6% vs. 30.7%; P < 0.001), and fewer patent lumbar vessels (56.9% vs. 83.1%; P = 0.001). The prevalence of endoleak at some point during follow-up was lower in group A (31.4% vs. 74% in group B; P < 0.001), and 100% of all aneurysmal growths were associated to the presence of endoleak. After 5 years, significant differences were observed in the growth-free rate (96.9% in group A vs. 85.2% in group B; hazard ratio [HR] 4.8 [1.1-21.4; P = 0.036]) and in the reintervention-free rate (95,7% vs. 84.6%; HR 6.6 [0.8-52.4; P = 0.07]). No reoperation in group A was due to type II endoleak. CONCLUSIONS: The aneurysmal sac can be expected to take a favorable course in those cases characterized by initial aneurysmal sac reduction. These findings may imply a change in the follow-up protocol, even in cases with type II endoleak.
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Aneurisma da Aorta Abdominal/cirurgia , Implante de Prótese Vascular , Procedimentos Endovasculares , Idoso , Idoso de 80 Anos ou mais , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aortografia , Implante de Prótese Vascular/efeitos adversos , Angiografia por Tomografia Computadorizada , Endoleak/diagnóstico por imagem , Endoleak/etiologia , Procedimentos Endovasculares/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do TratamentoRESUMO
OBJECTIVE: The present study describes an ambulatory, free skin micrograft technique with cyanoacrylate as a coadjuvant venous leg ulcer (VLU) healing strategy and its outcomes after one month. METHODS: This prospective study involved Comprehensive Classification System for Chronic Venous Disorders (CEAP) stage C6 patients with good granulation tissue and negative culture results, consecutively recruited in January 2017 in the Hospital Clinico San Carlos. A skin micrograft was harvested from the anterior surface of the patient's thigh with a 0.4cm punch (0.12cm2). The graft was adhered to the ulcer bed with cyanoacrylate. Anti-adherent dressing and double-layer bandaging was applied, with weekly replacements. Measurements were obtained of the surface of the VLU and graft progression (in cm2) using a photographic grid. RESULTS: A total of 12 VLUs in 12 patients were included, with a mean treated surface of 20.32±13.9cm2. A total of 18 grafts were placed and all were found to be viable after one week. Average graft growth was not noticeable after one week but was found to be 0.25±0.08cm2 after week two, 0.41±0.98cm2 after week three, and 0.70±0.15cm2 after week four (p<0.001). There were no complications in the donor zone. CONCLUSION: The findings of this study show that free skin micrografting with cyanoacrylate as outpatient treatment for VLUs was simple, rapid and without complication in this study, and may contribute to its wider application in clinical use.
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Autoenxertos , Bandagens , Cianoacrilatos , Úlcera da Perna/terapia , Transplante de Pele , Adesivos Teciduais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pacientes Ambulatoriais , Estudos Prospectivos , CicatrizaçãoRESUMO
Mixtures of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate with amphiphilic cosolvents, such as methanol and ethanol, nanoconfined between graphene walls are studied by means of molecular dynamics simulations and the results are compared with those of the pure ionic liquid and its mixtures with water confined in the same conditions. We investigate the adsorption of cosolvent molecules at the graphene walls as well as their distribution across the system. The results show that, due to a higher affinity of the polar groups to be close to the anions in combination with the electrostatic and excluded volume interactions, there exists a high tendency of the OH groups to lie close to the anode, inducing small changes in the first cation layer. The orientation of cosolvent molecules is found to be closely related to the alignment of the molecular dipole moment. We also investigate the lateral ionic distribution in the layers close to the electrodes, which shows a structural transition from liquid-like lamellar ordering to solid-like hexagonal patterns as the size of the cosolvent molecules increases leading to smaller position fluctuations of the ions. The dependence of the specific patterns on the nature of the electrodes is also studied. This study strongly suggests that the ionic patterns formed in the first ionic layers next to the charged interfaces are universal since their existence does not crucially depend on the atomic composition of the interfacial material, but only on the net charge density of the considered ionic layer, which significantly changes the ionic mobility in this region.
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BACKGROUND: The aim of this study is to analyze renal function impairment (RFI) after abdominal aortic aneurysm (AAA) repair in patients with preoperative chronic kidney disease (CKD). METHODS: Retrospective cohort study of patients with CKD undergoing elective AAA repair between 2008-2015, dividing the sample into two groups: open repair (OR) and endovascular repair (EVAR). The primary outcome was RFI defined by the RIFLE scale, studying Risk (1.5-fold increase in Cr or GFR decline >25% compared to baseline) and kidney injury (doubling of Cr or GFR decline >50%). RESULTS: Seventy-five patients (OR=29, EVAR=46). Baseline characteristics for OR and EVAR were similar except for age (70.4 vs. 77.2 years; P<0.001), coronary artery disease (31% vs. 56.5%; P=0.04), neck length (12.3 vs. 22.7 mm; P=0.001) and baseline GFR (40.6 vs. 36.9 mL/min; P=0.03). There were no inter-group differences in postoperative RFI: Risk of RFI 13.8% OR vs. 13% EVAR and kidney Injury 6.9% vs. 0% (P=0.19). There were also no differences in RFI at one year. Comparing GFR and Cr after surgery and at 12 months to baseline values, the OR group presented a significant postoperative decline in GFR compared to EVAR group (-3.8% vs. 11.1%; P=0.03), which had recovered at one-year follow-up (16.6% vs. 9.5%; P=0.43), while EVAR group presented with a tendency toward increased Cr during follow-up (-9.2% vs. 2.2%; P=0.08). Multivariate analysis did not identify independent RFI prognostic factors. CONCLUSIONS: Both techniques can be used safely in patients with CKD and baseline CKD is not a limiting factor for either technique. RFI is rare and transient in both groups.
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Aneurisma da Aorta Abdominal/cirurgia , Implante de Prótese Vascular , Procedimentos Endovasculares , Taxa de Filtração Glomerular , Rim/fisiopatologia , Insuficiência Renal Crônica/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Aneurisma da Aorta Abdominal/complicações , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/fisiopatologia , Biomarcadores/sangue , Implante de Prótese Vascular/efeitos adversos , Tomada de Decisão Clínica , Creatinina/sangue , Progressão da Doença , Procedimentos Endovasculares/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/diagnóstico , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do TratamentoRESUMO
Despite the growing interest in the potential electrochemical applications of both aluminium and ionic liquids in batteries, the microstructure of mixtures of trivalent salts and these dense ionic environments is completely unknown. In this work, the solvation of Al3+ cations in highly dense ionic solvents is investigated. For this purpose, molecular dynamics simulations of mixtures of a protic ionic liquid, ethylammonium nitrate (EAN), with aluminium nitrate (Al(NO3)3), both in bulk and confined between graphene walls, are performed. Several structural quantities of the system are calculated for different salt concentrations, such as densities, radial distribution functions, structure factors, coordination numbers and hydrogen bonds for the bulk mixture and ionic density profiles for the confined ones. Moreover, vibrational density of states is calculated for the salt cations, both in bulk and when close to the walls. The results obtained are analyzed and compared to those for mixtures of EAN with monovalent and divalent salts, in order to probe the influence of the salt cation charge on the system's properties. Finally, ab initio density functional theory calculations were performed in order to analyze the structure of the Al3+-ligand complexes, and their predictions for the Raman spectrum are compared both to the corresponding experimental one and the one coming from molecular dynamics simulations. According to our calculations, [Al(NO3)6]3- octahedral complexes do not significantly change the microstructure of the mixtures relative to those of Mg2+-based ones.
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We perform molecular dynamics simulations of mixtures of a prototypical protic ionic liquid, ethylammonium nitrate, with lithium or magnesium nitrate (LiNO3/Mg(NO3)2) confined between two graphene walls. The structure of the system is analyzed by means of ionic density profiles, angular orientations of ethylammonium cations close to the wall and the lateral structure of the first layer close to the graphene wall. All these results are compared to those of the corresponding aprotic ionic liquid systems, analyzing the influence of the graphene wall charge in the structure of the protic and aprotic mixtures. Moreover, vibrational densities of states are calculated for the salt cations close to the walls. Finally, we investigate the structure of the mixture with Li salt near the interface using ab initio density functional theory, and the results are compared with those obtained by classical molecular dynamics simulations.
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Mixtures of alkylammonium based protic ionic liquids and alkylmethylimidazolium based aprotic ionic liquids were studied by means of molecular dynamics simulations. Close to ideal mixing is observed in most studied magnitudes; however, the effect of increasing alkyl chain length in each of the cations is markedly different, with longer protic cations showing larger deviations, especially with regards to mixing enthalpy, which exhibits a strong compound forming tendency. The compound forming nature of these protic ionic liquids is shown to induce sharp changes in their local environment upon mixing.
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This paper extends the study of the induced temperature change in the mesostructure and in the physical properties occurring in aqueous mixtures of the ionic liquid 1-ethyl-3-methyl imidazolium octyl-sulfate [EMIm][OSO4]. For some compositions, these mixtures undergo a phase transition between the liquid (isotropic in the mesoscale) and the mesomorphic state (lyotropic liquid crystalline) at about room temperature. The behavior of mixtures doped with a divalent metal sulfate was investigated in order to observe their applicability as electrolytes. Calcium sulfate salt is almost insoluble even in the 20 wt% water mixture. The magnesium salt, in contrast, can be dissolved up to concentrations of 730 ppm in the same mixture and it has a profound impact on its properties. Six aqueous mixtures (with water content from 10 wt% to 33 wt%) of [EMIm][OSO4] were saturated with magnesium sulfate salt, producing the ternary mixture [EMIm][OSO4] + H2O + MgSO4. Viscosity, density and ionic conductivity for these samples were measured from 10 °C to 90 °C. In addition, SAXS, FTIR, diffussion NMR and Raman spectroscopy of the most interesting samples have been performed, and structural data indicate a transition between a hexagonal lyotropic liquid crystalline phase below and an isotropic solution phase above room temperature. The octyl sulfate anions of the cylindrical micelles in the hexagonal phase are coordinated with water molecules through H-bonds (about four per sulfate anion), while the [EMIm] cations seem to be poorly coordinated and so free to move. Inorganic salt addition reinforces that network, increasing the phase transition temperature.
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OBJECTIVE: This study investigated the influence of the aortic bifurcation anatomy on the endovascular treatment of abdominal aortic aneurysms using Excluder (W. L. Gore & Associates, Flagstaff, Ariz) bifurcated stent grafts. METHODS: This was a retrospective single-center study of patients treated with the Excluder stent graft. Analysis included anatomical factors of the aortic bifurcation (aortic bifurcation diameter [ABD], calcification, thrombus), characteristics of the stent graft limbs (sum of stent graft limbs diameters [SLD]), and the SLD/ABD ratio. Narrow bifurcation was defined as ABD <20 mm. Primary outcomes were intraoperative stenosis, need for additional intraoperative measures, limb stenosis, and occlusion during follow-up. RESULTS: The study included 232 patients. Mean ABD was 24.6 ± 6 mm, with 53 patients (23%) presenting with narrow bifurcation (range, 12.5-19.5 mm). Median SLD in these patients was 28 mm, and the SLD/ABD ratio was 1.64. Calcification involving >50% of the bifurcation circumference was present in 32% of the patients, with 17% presenting thrombus in this area. Of 53 patients with narrow bifurcation, intraoperative stenosis >50% occurred in three (5.7%), which required adjunctive treatment. Computed tomography at 1 month showed limb stenosis >50% in nine patients (17%). No limb occlusions were recorded with a median follow-up of 34 months. Multivariate analysis of the overall series showed a higher risk of limb stenosis on the computed tomography at 1 month in patients with peripheral artery disease (hazard ratio [HR], 5.3; 95% confidence interval [CI], 1.2-24.4; P = .032), narrow bifurcation (HR, 5.7; 95% CI, 2-15.8; P = .001), higher SLD/ABD ratio (HR, 29.3; 95% CI, 4-215.2; P = .001), and calcium >50% (HR, 3; 95% CI, 1.1-8; P = .03), and lower in bifurcations with thrombus (HR, 0.3; 95% CI, 0.1-0.8; P = .017). CONCLUSIONS: Abdominal aortic aneurysms with narrow bifurcation can be treated with the bifurcated Excluder device without additional adjunctive measures. The presence of limb stenosis during follow-up is not associated with occlusion. Long-term follow-up studies are needed to confirm these results.
Assuntos
Aneurisma da Aorta Abdominal/cirurgia , Implante de Prótese Vascular/instrumentação , Constrição Patológica/epidemiologia , Procedimentos Endovasculares/instrumentação , Oclusão de Enxerto Vascular/epidemiologia , Doença Arterial Periférica/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Aorta Abdominal/anatomia & histologia , Aorta Abdominal/diagnóstico por imagem , Aorta Abdominal/cirurgia , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aortografia/métodos , Prótese Vascular/efeitos adversos , Prótese Vascular/estatística & dados numéricos , Implante de Prótese Vascular/efeitos adversos , Implante de Prótese Vascular/métodos , Angiografia por Tomografia Computadorizada/métodos , Constrição Patológica/diagnóstico por imagem , Constrição Patológica/etiologia , Procedimentos Endovasculares/efeitos adversos , Procedimentos Endovasculares/métodos , Extremidades , Feminino , Oclusão de Enxerto Vascular/diagnóstico por imagem , Oclusão de Enxerto Vascular/etiologia , Humanos , Masculino , Doença Arterial Periférica/complicações , Desenho de Prótese , Estudos Retrospectivos , Fatores de Risco , Stents/efeitos adversos , Stents/estatística & dados numéricos , Resultado do Tratamento , Grau de Desobstrução VascularRESUMO
We perform molecular dynamics simulations of ionic liquids confined between graphene walls under a large variety of conditions (pure ionic liquids, mixtures with water and alcohols, mixtures with lithium salts and defective graphene walls). Our results show that the formation of striped and hexagonal patterns in the Stern layer can be considered as a general feature of ionic liquids at electrochemical interfaces, the transition between patterns being controlled by the net balance of charge in the innermost layer of adsorbed molecules. This explains previously reported experimental and computational results and, for the first time, why these pattern changes are triggered by any perturbation of the charge density at the innermost layer of the electric double layer (voltage and composition changes, and vacancies at the electrode walls, among others), which may help tuning electrode-ionic liquid interfaces. Using Monte Carlo simulations we show that such structures can be reproduced by a simple two-dimensional lattice model with only nearest-neighbour interactions, governed by highly screened ionic interactions and short-range and excluded volume interactions. We also show that the results of our simulations are consistent with those inferred from the Landau-Brazovskii theory of pattern formation in self-assembling systems. The presence of these patterns at the ionic liquid graphene-electrode interfaces may have a strong impact on the process of ionic transfer from the bulk mixtures to the electrodes, on the differential capacitance of the electrode-electrolyte double layer or on the rates of redox reactions at the electrodes, among other physicochemical properties, and is therefore an effect of great technological interest.
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The structural and dynamical properties of bulk mixtures of long-chained primary and secondary alcohols (propanol, butanol, and 2-pentanol) with protic ionic liquids (ethylammonium and butylammonium nitrate) were studied by means of molecular dynamics simulations and small angle X-ray scattering (SAXS). Changes in the structure with the alcohol concentration and with the alkyl chain length of the alcohol moieties were found, showing variations in the radial distribution function and in the number of hydrogen bonds in the bulk liquids. Moreover, the structural behaviour of the studied mixtures is further clarified with the spatial distribution functions. The global picture in the local scale is in good agreement with the nanostructured solvation paradigm [T. Méndez-Morales et al. Phys. Chem. B 118, 761 (2014)], according to which alcohols are accommodated into the hydrogen bonds' network of the ionic liquid instead of forming clusters in the bulk. Indeed, our study reveals that the alcohol molecules are placed with their polar heads at the interfaces between polar and nonpolar nanodomains in the ionic liquid, with their alkyl chains inside the nonpolar organic nanodomains. The influence of alcohol chain length in the single-particle dynamics of the mixtures is also reported calculating the velocity autocorrelation function and vibrational densities of states of the different species in the ionic liquid-alcohol mixtures, and a weak caging effect for the ethylammonium cations independent of the chain size of the alcohols was found. However, the SAXS data collected for the studied mixtures show an excess of the scattering intensities which indicates that there are also some structural heterogeneities at the nanoscale.
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A molecular dynamics study of mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) with magnesium tetrafluoroborate (Mg[BF4]2) confined between two parallel graphene walls is reported. The structure of the system is analyzed by means of ionic density profiles, lateral structure of the first layer close to the graphene surface and angular orientations of imidazolium cations. Free energy profiles for divalent magnesium cations are calculated using two different methods in order to evaluate the height of the potential barriers near the walls, and the results are compared with those of mixtures of the same ionic liquid and a lithium salt (Li[BF4]). Preferential adsorption of magnesium cations is analyzed using a simple model and compared to that of lithium cations, and vibrational densities of states are calculated for the cations close to the walls analyzing the influence of the graphene surface charge. Our results indicate that magnesium cations next to the graphene wall have a roughly similar environment to that in the bulk. Moreover, they face higher potential barriers and are less adsorbed on the charged graphene walls than lithium cations. In other words, magnesium cations have a more stable solvation shell than lithium ones.
RESUMO
Molecular dynamics simulations of mixtures of the protic ionic liquid ethylammonium nitrate (EAN) and the aprotic 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) are reported and the results are compared with experimental density and electrical conductivity measurements. Essentially ideal mixing of the ionic liquids is seen to take place by means of experimental and simulated excess molar volumes, whose very low values suggest a gradual transition between the structures of the two end constituents of the mixture. A weak dominance of the structure of the protic ionic liquid is nevertheless registered, due to a slight preferential formation of the network of hydrogen bonds, as reflected in the coordination number and the number of hydrogen bonds in the mixture. A novel conductivity curve showing pronounced deviations from the simple ideal mixing rule is reported, with three different regions defined by a local maximum - reflecting enhanced translational dynamics relative to ideal mixture behaviour - and a global minimum at intermediate concentrations. The physical origin of this behaviour is discussed along with the structure and single-particle dynamics of the mixture, and it is seen that these regions are defined by the onset of the formation of the EAN hydrogen bonded network (xEAN = 0.2) and the virtual disappearance of the structure of the aprotic ionic liquid at xEAN = 0.7. It is concluded that the delicate interplay between both networks has a deep effect on the placement and mobility of [EMIM](+) cations in the mixture all throughout the different stages of the structural transition, which seems to be the driving force behind the reported transport properties of the mixture at intermediate to high EAN concentrations.