Cardiac index-guided therapy to maintain optimised postinduction cardiac index in high-risk patients having major open abdominal surgery: the multicentre randomised iPEGASUS trial.

BACKGROUND: It is unclear whether optimising intraoperative cardiac index can reduce postoperative complications. We tested the hypothesis that maintaining optimised postinduction cardiac index during and for the first 8 h after surgery reduces the incidence of a composite outcome of complications within 28 days after surgery compared with routine care in high-risk patients having elective major open abdominal surgery. METHODS: In three German and two Spanish centres, high-risk patients having elective major open abdominal surgery were randomised to cardiac index-guided therapy to maintain optimised postinduction cardiac index (cardiac index at which pulse pressure variation was <12%) during and for the first 8 h after surgery using intravenous fluids and dobutamine or to routine care. The primary outcome was the incidence of a composite outcome of moderate or severe complications within 28 days after surgery. RESULTS: We analysed 318 of 380 enrolled subjects. The composite primary outcome occurred in 84 of 152 subjects (55%) assigned to cardiac index-guided therapy and in 77 of 166 subjects (46%) assigned to routine care (odds ratio: 1.87, 95% confidence interval: 1.03-3.39, P=0.038). Per-protocol analyses confirmed the results of the primary outcome analysis. CONCLUSIONS: Maintaining optimised postinduction cardiac index during and for the first 8 h after surgery did not reduce, and possibly increased, the incidence of a composite outcome of complications within 28 days after surgery compared with routine care in high-risk patients having elective major open abdominal surgery. Clinicians should not strive to maintain optimised postinduction cardiac index during and after surgery in expectation of reducing complications. CLINICAL TRIAL REGISTRATION: NCT03021525.

Systemic Inflammation in Oncologic Patients Undergoing Systemic Treatment and Receiving Whey Protein-Based Nutritional Support.

There is increasing evidence about the role of inflammation in sarcopenia and tumor progression; thus, its modulation would represent a valuable strategy for improving clinical outcomes in patients with cancer. Several studies have reported that whey protein has significant anti-inflammatory and antioxidant characteristics in humans. We aimed to evaluate the effects of whey protein-based oral nutritional support on circulating cytokines in patients with solid tumors undergoing systemic treatment. Forty-six patients with solid tumors of different origin and undergoing systemic treatment were evaluated. Nutritional support with two daily whey protein-based oral supplements was administered. Circulating levels of IL-6, IL-8, IL-10, MCP-1 and IP-10 were determined. Nutritional evaluation included anthropometric, instrumental and biochemical parameters. Over 63% of the evaluated patients underwent surgery, 56.5% required chemotherapy and almost 50% received combined treatment. Patients with resected primary tumor presented with lower baseline IL-6 (p < 0.05) and IP-10 (p < 0.001); after three months of nutritional support, they presented with lower IL-8 (p < 0.05) and tended to present lower IL-6 and IP-10 (p = 0.053 and 0.067, respectively). Significant positive correlations between circulating cytokines, C-reactive protein and ferritin were observed; similarly, negative correlations with anthropometric and biochemical nutritional parameters were noticed (p < 0.05). We did not observe significant changes in circulating cytokine levels (IL-6, IL-8, IL-10, MCP-1 and IP-10) in patients with cancer undergoing systemic treatment after three months of nutritional support with whey protein-based oral supplements. According to a univariate analysis in our cohort, circulating IL-8 was associated with mortality in these patients, additionally, MCP-1 and IP-10 tended to correlate; but an age- and sex-adjusted multivariate analysis revealed that only baseline MCP-1 was significantly associated with mortality (OR 1.03 (95% CI: 1.00-1.05)). In conclusion, surgery of the primary solid tumor and combination treatment allow significant reduction in circulating cytokine levels, which remained stable while patients received nutritional support with whey protein-based oral supplements over three months. The role of MCP-1 as an independent factor for mortality in these patients should be further evaluated.

mtDNA Single-Nucleotide Variants Associated with Type 2 Diabetes.

Type 2 diabetes (T2D) is a chronic systemic disease with a complex etiology, characterized by insulin resistance and mitochondrial dysfunction in various cell tissues. To explore this relationship, we conducted a secondary analysis of complete mtDNA sequences from 1261 T2D patients and 1105 control individuals. Our findings revealed significant associations between certain single-nucleotide polymorphisms (SNPs) and T2D. Notably, the variants m.1438A>G (rs2001030) (controls: 32 [27.6%], T2D: 84 [72.4%]; OR: 2.46; 95%CI: 1.64-3.78; p < 0.001), m.14766C>T (rs193302980) (controls: 498 [36.9%], T2D: 853 [63.1%]; OR: 2.57, 95%CI: 2.18-3.04, p < 0.001), and m.16519T>C (rs3937033) (controls: 363 [43.4%], T2D: 474 [56.6%]; OR: 1.24, 95%CI: 1.05-1.47, p = 0.012) were significantly associated with the likelihood of developing diabetes. The variant m.16189T>C (rs28693675), which has been previously documented in several studies across diverse populations, showed no association with T2D in our analysis (controls: 148 [13.39] T2D: 171 [13.56%]; OR: 1.03; 95%CI: 0.815-1.31; p = 0.83). These results provide evidence suggesting a link between specific mtDNA polymorphisms and T2D, possibly related to association rules, topological patterns, and three-dimensional conformations associated with regions where changes occur, rather than specific point mutations in the sequence.

Effect of an individualized versus standard pneumoperitoneum pressure strategy on postoperative recovery: a randomized clinical trial in laparoscopic colorectal surgery.

BACKGROUND: It remains uncertain whether individualization of pneumoperitoneum pressures during laparoscopic surgery improves postoperative recovery. This study compared an individualized pneumoperitoneum pressure (IPP) strategy with a standard pneumoperitoneum pressure (SPP) strategy with respect to postoperative recovery after laparoscopic colorectal surgery. METHODS: This was a multicentre RCT. The IPP strategy comprised modified patient positioning, deep neuromuscular blockade, and abdominal wall prestretching targeting the lowest intra-abdominal pressure (IAP) that maintained acceptable workspace. The SPP strategy comprised patient positioning according to the surgeon's preference, moderate neuromuscular blockade and a fixed IAP of 12 mmHg. The primary endpoint was physiological postoperative recovery, assessed by means of the Postoperative Quality of Recovery Scale. Secondary endpoints included recovery in other domains and overall recovery, the occurrence of intraoperative and postoperative complications, duration of hospital stay, and plasma markers of inflammation up to postoperative day 3. RESULTS: Of 166 patients, 85 received an IPP strategy and 81 an SPP strategy. The IPP strategy was associated with a higher probability of physiological recovery (odds ratio (OR) 2·77, 95 per cent c.i. 1·19 to 6·40, P = 0·017; risk ratio (RR) 1·82, 1·79 to 1·87, P = 0·049). The IPP strategy was also associated with a higher probability of emotional (P = 0·013) and overall (P = 0·011) recovery. Intraoperative adverse events were less frequent with the IPP strategy (P < 0·001) and the plasma neutrophil-lymphocyte ratio was lower (P = 0·029). Other endpoints were not affected. CONCLUSION: In this cohort of patients undergoing laparoscopic colorectal surgery, an IPP strategy was associated with faster recovery, fewer intraoperative complications and less inflammation than an SPP strategy. Registration number: NCT02773173 ( http://www.clinicaltrials.gov).

ANTECEDENTES: No se sabe con certeza si individualizar las presiones del neumoperitoneo durante la cirugía laparoscópica mejora la recuperación postoperatoria. Comparamos una estrategia con individualización de la presión del neumoperitoneo (individualised pneumoperitoneum pressure, IPP) frente a una estrategia con presión estándar del neumoperitoneo (standard pneumoperitoneum pressure, SPP) respecto a la recuperación postoperatoria tras cirugía colorrectal laparoscópica. MÉTODOS: Ensayo clínico aleatorizado multicéntrico. La estrategia IPP consistió en una modificación de la posición, bloqueo neuromuscular profundo, y una distensión de la pared abdominal conseguida con la presión intraabdominal (intra-abdominal pressure, IAP) más baja en la que el espacio quirúrgico operativo siguiera siendo aceptable. La estrategia SPP consistió en una posición de acuerdo con la preferencia del cirujano, bloqueo neuromuscular moderado, e IAP fija de 12 mm Hg. El resultado primario fue la recuperación fisiológica postoperatoria, evaluada mediante la escala de calidad en la recuperación postoperatoria (Postoperative Quality of Recovery Scale, PQRS). Los resultados secundarios incluyeron la recuperación en otros dominios y la recuperación global, la aparición de complicaciones intraoperatorias y postoperatorias, duración de la estancia hospitalaria, y los valores de los marcadores inflamatorios séricos durante tres días postoperatorios. RESULTADOS: De un total de 166 pacientes, 85 recibieron una estrategia IPP y 81 una estrategia SPP. La estrategia IPP se asoció con una elevada probabilidad de recuperación fisiológica (razón de oportunidades, odds ratio OR, 2,8 (i.c. del 95% 1,2-6,4); P = 0,017, razón de riesgo, 1,8 (i.c. del 95% 1,7-1,9), P = 0,05)). La estrategia IPP también se asoció con una elevada probabilidad de recuperación emotiva (P = 0,013) y global (P = 0,011). Los eventos adversos intraoperatorios fueron menos frecuentes con la estrategia IPP (P < 0,001) y la tasa neutrófilo-linfocito fue más baja (P = 0,029). No se observaron cambios en otras variables. CONCLUSIÓN: En esta cohorte de pacientes sometidos a cirugía colorrectal laparoscópica, una estrategia IPP se asoció con una recuperación más rápida, menos complicaciones intraoperatorias y menos inflamación en comparación con una estrategia SPP.

Intraabdominal Pressure Targeted Positive End-expiratory Pressure during Laparoscopic Surgery: An Open-label, Nonrandomized, Crossover, Clinical Trial.

BACKGROUND: Pneumoperitoneum for laparoscopic surgery is associated with a rise of driving pressure. The authors aimed to assess the effects of positive end-expiratory pressure (PEEP) on driving pressure at varying intraabdominal pressure levels. It was hypothesized that PEEP attenuates pneumoperitoneum-related rises in driving pressure. METHODS: Open-label, nonrandomized, crossover, clinical trial in patients undergoing laparoscopic cholecystectomy. "Targeted PEEP" (2 cm H2O above intraabdominal pressure) was compared with "standard PEEP" (5 cm H2O), with respect to the transpulmonary and respiratory system driving pressure at three predefined intraabdominal pressure levels, and each patient was ventilated with two levels of PEEP at the three intraabdominal pressure levels in the same sequence. The primary outcome was the difference in transpulmonary driving pressure between targeted PEEP and standard PEEP at the three levels of intraabdominal pressure. RESULTS: Thirty patients were included and analyzed. Targeted PEEP was 10, 14, and 17 cm H2O at intraabdominal pressure of 8, 12, and 15 mmHg, respectively. Compared to standard PEEP, targeted PEEP resulted in lower median transpulmonary driving pressure at intraabdominal pressure of 8 mmHg (7 [5 to 8] vs. 9 [7 to 11] cm H2O; P = 0.010; difference 2 [95% CI 0.5 to 4 cm H2O]); 12 mmHg (7 [4 to 9] vs.10 [7 to 12] cm H2O; P = 0.002; difference 3 [1 to 5] cm H2O); and 15 mmHg (7 [6 to 9] vs.12 [8 to 15] cm H2O; P < 0.001; difference 4 [2 to 6] cm H2O). The effects of targeted PEEP compared to standard PEEP on respiratory system driving pressure were comparable to the effects on transpulmonary driving pressure, though respiratory system driving pressure was higher than transpulmonary driving pressure at all intraabdominal pressure levels. CONCLUSIONS: Transpulmonary driving pressure rises with an increase in intraabdominal pressure, an effect that can be counterbalanced by targeted PEEP. Future studies have to elucidate which combination of PEEP and intraabdominal pressure is best in term of clinical outcomes.

In vitro lead tolerance and accumulation in three Chrysanthemum cultivars for phytoremediation purposes with ornamental plants.

The use of ornamental plants for the phytoremediation of potentially toxic elements in polluted soils is an interesting task. It makes possible to combine environmental restoration, re-use of land, and the production of goods and services of economic interest. In this work, in vitro experiments using three cultivars of Chrysanthemum (Asteraceae) were carried out with 0, 300, 600, 900, and 1500 mg/kg of lead concentrations for a period of 12 weeks. The objective was to obtain data about their lead tolerance and bioaccumulation capacity in order to know their potential as phytoremediators in a densely populated Caribbean area of the Dominican Republic with a high concentration of lead in soils. The variations in biomass, root growth as well as accumulation of this element in the plants were measured. The results suggest that the three cultivars have a good potential for phytoextraction at moderate pollution levels, as they showed a good bioaccumulation of lead, which had mild effects on their biomass production and root elongation. Additional studies should be carried out to assess their effectiveness as phytoextractors under field conditions, as well as other alternative uses that could generate esthetic, environmental, and/or economic benefits for tropical areas contaminated by Pb.

A multifaceted individualized pneumoperitoneum strategy for laparoscopic colorectal surgery: a multicenter observational feasibility study.

BACKGROUND: While guidelines for laparoscopic abdominal surgery advise using the lowest possible intra-abdominal pressure, commonly a standard pressure is used. We evaluated the feasibility of a predefined multifaceted individualized pneumoperitoneum strategy aiming at the lowest possible intra-abdominal pressure during laparoscopic colorectal surgery. METHODS: Multicenter prospective study in patients scheduled for laparoscopic colorectal surgery. The strategy consisted of ventilation with low tidal volume, a modified lithotomy position, deep neuromuscular blockade, pre-stretching of the abdominal wall, and individualized intra-abdominal pressure titration; the effect was blindly evaluated by the surgeon. The primary endpoint was the proportion of surgical procedures completed at each individualized intra-abdominal pressure level. Secondary endpoints were the respiratory system driving pressure, and the estimated volume of insufflated CO2 gas needed to perform the surgical procedure. RESULTS: Ninety-two patients were enrolled in the study. Fourteen cases were converted to open surgery for reasons not related to the strategy. The intervention was feasible in all patients and well-accepted by all surgeons. In 61 out of 78 patients (78%), surgery was performed and completed at the lowest possible IAP, 8 mmHg. In 17 patients, IAP was raised up to 12 mmHg. The relationship between IAP and driving pressure was almost linear. The mean estimated intra-abdominal CO2 volume at which surgery was performed was 3.2 L. CONCLUSION: A multifaceted individualized pneumoperitoneum strategy during laparoscopic colorectal surgery was feasible and resulted in an adequate working space in most patients at lower intra-abdominal pressure and lower respiratory driving pressure. ClinicalTrials.gov (Trial Identifier: NCT03000465).

Thermoelectric Properties of Doped-Cu3SbSe4 Compounds: A First-Principles Insight.

This work reports the first systematic study of the effects of substitutional doping on the transport properties and electronic structure of Cu3SbSe4. To this end, the electronic structures and thermoelectric parameters of Cu3SbSe4 and Cu3Sb1- xM xSe4 (M = Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Bi) were systematically investigated by using density functional theory and the Boltzmann semiclassical transport theory. Substitutional doping at Sb site with IIIA (M = Al, Ga, In, Tl) and IVA (M = Si, Ge, Sn, Pb) elements considerably increases the hole carrier concentration and consequently the electrical conductivity, while doping with M = Bi would be adequate to provide high S values. Changes in calculated thermoelectric parameters are explained based on the effects of the dopant element on the electronic band structure near the Fermi level. We also present an extensive comparison between thermoelectric parameters here calculated and available experimental data. Our results allow us to infer significant insights into the search for new materials with improved thermoelectric performance by modifying the electronic structure through substitutional doping.

Simultaneous CO2 and SO2 capture by using ionic liquids: a theoretical approach.

Density functional theory (DFT) methods were used to analyze the mechanism of interaction between acidic gases and ionic liquids based on the 1-ethyl-3-methylimidazolium cation coupled with five different anions. Single ion pairs and ionic clusters containing six ion pairs were used to model the interactions of the ionic liquids with acidic gas molecules. The properties of the systems were analyzed based on geometric properties, interaction energies and Bader's theory. The cluster approach gives a more accurate representation of the behavior of ions and gases in the bulk liquid phase, and despite computational challenges, the cluster approach allows us to quantify interactions beyond short range ones used in the single ion pair-acidic gas model commonly applied in the literature. The results reported herein point out efficient simultaneous capturing of both gases especially for ionic liquids containing the acetate anion.

Variations in diabetes remission rates after bariatric surgery in Spanish adults according to the use of different diagnostic criteria for diabetes.

BACKGROUND: There are multiple criteria to define remission of type 2 diabetes (DM2) after bariatric surgery but there is not a specific one widely accepted. Our objectives were to compare diagnostic criteria for DM2 remission after bariatric surgery: Criteria from Spanish scientific associations (SEEN/SEEDO/SED) and from the American Diabetes Association (ADA). We also aim to analyse the degree of correlation between these sets of criteria. METHODS: Retrospective observational study in 127 patients undergoing bariatric surgery in a single centre (Hospital Universitario Reina Sofía, Córdoba, Spain) between January 2001 and December 2009. We analysed DM2 remission following bariatric surgery comparing DM2 diagnostic criteria approved by Spanish scientific associations and ADA criteria. RESULTS: In total, 62.2% of patients were women; mean age was 47.1 years. Following surgery, 52% achieved complete remission according to ADA criteria, and 63.8% following the criteria approved by Spanish associations (p = 0.001);18.9 and 8.7%, respectively, showed partial remission (p = 0.007), and 29.1 and 27.6% no remission, according to the criteria approved by each association (p = 0.003). There was good correlation between both sets of criteria (Rho 0.781; p < 0.001). CONCLUSIONS: In our series, using more stringent criteria for defining DM2 remission (ADA criteria) results in a lower rate of remission, although we found a a high degree of correlation between both sets of criteria.

In silico rational design of ionic liquids for the exfoliation and dispersion of boron nitride nanosheets.

A requirement for exploiting most of the unique properties of boron-nitride (BN) nanosheets is their isolation from the bulk material. A rational design of task-specific ionic liquids (ILs) through DFT simulations is reported in this work. The applied computational protocol allowed the screening of large IL families, which was carried out bearing in mind the achievement of strong π-π stacking between the anions and BN nanosheets as well as a negative charge transfer from the anion to the surface. The selected ionic liquids yielded strong interaction energies with BN nanosheets and high charge transfer values, while the main features of the ionic liquid are not affected in the presence of nanosheets. DFT simulations provided a detailed picture of the interaction mechanism and useful structure-property relationships in the search of a new ionic liquid for BN exfoliation.

Flavonol-carbon nanostructure hybrid systems: a DFT study on the interaction mechanism and UV/Vis features.

Flavonols are a class of natural compounds with potential biological and pharmacological applications. They are also natural pigments responsible for the diversity of colors in plants. Flavonols offer the possibility of tuning their features through chemical functionalization as well as the presence of an aromatic backbone, which could lead to non-covalent interactions with different nanostructures or aromatic molecules. In this work, a protocol based on ONIOM (QM/QM) calculations to investigate the structural features (binding energies, intermolecular interactions) of flavonols interacting with the surface of several carbon nanostructures (such as graphene, fullerene C60 and carbon nanotubes) is developed. The confinement of flavonols inside carbon nanotubes has also been studied. Three flavonols, galangin, quercetin and myricetin, as well as pristine flavone were selected. Special attention has also been paid to the changes in UV/Vis features of flavonols due to the interaction with carbon nanostructures. Our results point out that π-stacking interactions are the driving force for the adsorption onto carbon nanostructures as well as for the confinement inside carbon nanotubes. Likewise, UV/Vis features of flavonols could be fine-tuned through the interaction with suitable carbon nanostructures.

DFT study of the effect of fluorine atoms on the crystal structure and semiconducting properties of poly(arylene-ethynylene) derivatives.

The effect of fluorine substitution on the molecular structure, crystal packing, and n-type semiconducting properties of a set of poly(arylene-ethynylene) polymers based on alternating thiadiazole and phenyl units linked through ethynylene groups has been studied by means of Density Functional Theory. As a result, an enlargement in the interplanar distance between cofacial polymer chains, as well as a decrease of the electronic coupling and electron mobility is predicted. On the other hand, fluorination could facilitate electron injection into the material. A polymer containing both alkoxy pendant chains and fluorine atoms is proposed as a compromise solution between efficiency of electron injection and charge transport within the material.

Effect of five-membered ring and heteroatom substitution on charge transport properties of perylene discotic derivatives: A theoretical approach.

Density functional theory calculations were carried out to investigate the evolvement of charge transport properties of a set of new discotic systems as a function of ring and heteroatom (B, Si, S, and Se) substitution on the basic structure of perylene. The replacement of six-membered rings by five-membered rings in the reference compound has shown a prominent effect on the electron reorganization energy that decreases ∼0.2 eV from perylene to the new carbon five-membered ring derivative. Heteroatom substitution with boron also revealed to lower the LUMO energy level and increase the electron affinity, therefore lowering the electron injection barrier compared to perylene. Since the rate of the charge transfer between two molecules in columnar discotic systems is strongly dependent on the orientation of the stacked cores, the total energy and transfer integral of a dimer as a disc is rotated with respect to the other along the stacking axis have been predicted. Aimed at obtaining a more realistic approach to the bulk structure, the molecular geometry of clusters made up of five discs was fully optimized, and charge transfer rate and mobilities were estimated for charge transport along a one dimensional pathway. Heteroatom substitution with selenium yields electron transfer integral values ∼0.3 eV with a relative disc orientation of 25°, which is the preferred angle according to the dimer energy profile. All the results indicate that the tetraselenium-substituted derivative, not synthetized so far, could be a promising candidate among those studied in this work for the fabrication of n-type semiconductors based on columnar discotic liquid crystals materials.

A density functional theory insight towards the rational design of ionic liquids for SO2 capture.

A systematic density functional theory (DFT) analysis has been carried out to obtain information at the molecular level on the key parameters related to efficient SO2 capture by ionic liquids (ILs). A set of 55 ILs, for which high gas solubility is expected, has been selected. SO2 solubility of ILs was firstly predicted based on the COSMO-RS (Conductor-like Screening Model for Real Solvents) method, which provides a good prediction of gas solubility data in ILs without prior experimental knowledge of the compounds' features. Then, interactions between SO2 and ILs were deeply analyzed through DFT simulations. This work provides valuable information about required factors at the molecular level to provide high SO2 solubility in ILs, which is crucial for further implementation of these materials in the future. In our opinion, systematic research on ILs for SO2 capture increases our knowledge about those factors which could be controlled at the molecular level, providing an approach for the rational design of task-specific ILs.

Adsorption of choline benzoate ionic liquid on graphene, silicene, germanene and boron-nitride nanosheets: a DFT perspective.

The adsorption of choline benzoate ([CH][BE]) ionic liquid (IL) on the surface of different hexagonal nanosheets has been studied using Density Functional Theory (DFT) methods. For this, the interaction mechanism, binding energies and electronic structure of [CH][BE] ionic liquid on four types of nanosheets, i.e., graphene, silicene, germanene and boron-nitride, were estimated and compared. The adsorption of [CH][BE] ionic liquid on different nanosheets is mainly featured by van der Waals forces, leading to strong benzoate ion-surface π-stacking. Likewise, there is also an important charge transfer from the anion to the sheet. The electronic structure analysis shows that Si- and Ge-based sheets lead to the largest changes in the HOMO and LUMO levels of choline benzoate. This paper provides new insights into the capability of DFT methods to provide useful information about the adsorption of ionic liquids on nanosheets and how ionic liquid features could be tuned through the adsorption on the suitable nanosheet.

Assessment of DFT methods for studying acid gas capture by ionic liquids.

For the first time, this work reports an analysis of the performance of Density Functional methods for studying acid gas capture (CO2 and SO2) by ionic liquids (ILs). The considered functionals were selected as representatives of the available families: pure GGA (PBE and BLYP), hybrid (PBE0 and B3LYP), hybrid meta-GGA (M06, M06-2X and M06-HF), long range corrected (LC-PBEPBE, CAM-B3LYP, ωB97X) and dispersion corrected (PBE-D2, B3LYP-D2 and ωB97XD). Likewise, HF and MP2 were also applied. Binding energies of cation-anion interacting pairs as well as IL-CO2 and IL-SO2 systems were calculated for a set of 54 ILs and compared against MP2/aug-cc-pvDZ. Unlike previously reported DFT benchmarks on ILs, which calculated binding energies through single point calculations on fixed geometries, properties in this work were calculated for geometries optimized at each theoretical level. DFT functionals that are suitable for describing ion-ion and ion-gas interactions were identified, considering both Coulombic forces and dispersion interactions. The reported results allowed us to infer relationships to the rational design of ILs for acid gas capture.

A detailed study of cholinium chloride and levulinic acid deep eutectic solvent system for CO2 capture via experimental and molecular simulation approaches.

Choline chloride + levulinic acid deep eutectic solvent is studied as a suitable material for CO2 capturing purposes. The most relevant physicochemical properties of this solvent are reported together with the CO2 solubility as a function of temperature. The corrosivity of this solvent is studied showing better performance than amine-based solvents. A theoretical study using both density functional theory and molecular dynamics approaches is carried out to analyze the properties of this fluid from the nanoscopic viewpoint, and their relationship with the macroscopic behavior of the system and its ability for CO2 capturing. The behavior of the liquid-gas interface is also studied and its role on the CO2 absorption mechanism is analyzed. The reported combined experimental and theoretical approach leads to a complete picture of the behavior of this new sorbent with regard to CO2, which together with its low cost, and the suitable environmental and toxicological properties of this solvent, lead to a promising candidate for CO2 capturing technological applications.

A DFT approach to the charge transport related properties in columnar stacked π-conjugated N-heterocycle cores including electron donor and acceptor units.

We present a density functional theory (DFT) study on charge-transport related properties in a series of discotic systems based on 1,3,5-triazine and tris[1,2,4]triazolo[1,3,5]triazine central cores as electron acceptor units, and phenyl-thiophene and N-carbazolyl-thiophene segments as electron donor units. The presence of both electron donor and acceptor moieties in the π-conjugated core could lead to new discotic liquid crystal (DLC) materials which are predicted to display ambipolar charge transport behavior in such a way that electrons could move through the central part of the next cores while holes mainly do through the peripheral groups. A significant increase in hole mobility when N-carbazolyl is present as an electron donor unit in the peripheral region is predicted. In addition, a detailed topological analysis of the electron charge density within the framework provided by Quantum Theory of Atoms in Molecules (QTAIM) has been performed in order to characterize intra- and intermolecular interactions in terms of hydrogen bonds and/or π···π stacking which contribute to the stabilization of the columnar stack and the helical self-assembly at the molecular scale.

Structural Diversity of Class 1 Integrons in Multiresistant Strains of Escherichia coli Isolated from Patients in a Hospital in Mexico City.

Since a decade, Escherichia coli has been considered an important nosocomial pathogen due to the high number of isolates multiresistant to antimicrobials reported worldwide. In clinical and environmental strains, transposons, plasmids, and integrons are currently considered the principal genetic elements responsible for the acquisition of antibiotic resistance through horizontal transfer. The objective of this research was to correlate the resistance to antibiotics of E. coli clinical strains with the presence class I integrons. In the present study, one hundred E. coli strains were isolated and tested for susceptibility and resistance to antimicrobials. Class 1 integrons were detected by PCR, and the arrangement of gene cassettes was determined by sequencing. Twenty two strains were found to carry Class 1 integrons. Sequence analysis of the variable regions revealed the presence of several gene cassettes, such as dihydrofolate reductases (dfr2d, dfrA17, and dhfrXVb), adenylyl transferases (aadA2, addA5, and addA22), and chloramphenicol efflux pump (cmlA), and oxacillinase (bla OXA-1 ). The dfrA17-addA5 arrangement prevailed upon other integrons in the study. This is the first report of the presence of the dfr2d and dhfrXVb-aadA2 cassette arrangements in a Class 1 integrons from clinical strains of E. coli. In most of the strains, it was found a direct relationship between genetic arrangements and resistance phenotypes. Four integrons were detected in plasmids that might be involved in the resistance genes transfer to other bacteria of clinical importance. Our results confirm the presence of Class 1 integrons and their essential role in the dissemination of resistance cassettes among E. coli strains.