Selective adsorption of sulphur dioxide and hydrogen sulphide by metal-organic frameworks.

The removal of highly toxic gasses such as SO2 and H2S is important in various industrial and environmental applications. Metal organic frameworks (MOFs) are promising candidates for the capture of toxic gases owing to their favorable properties such as high selectivity, moisture stability, thermostability, acid gas resistance, high sorption capacity, and low-cost regenerability. In this study, we perform first principles density functional theory (DFT) and grand-canonical Monte Carlo (GCMC) simulations to investigate the capture of highly toxic gases, SO2 and H2S, by the recently designed ZTF and MAF-66 MOFs. Our results indicate that ZTF and MAF-66 show good adsorption performances for SO2 and H2S capture. The nature of the interactions between H2S or SO2 and the pore surface cavities was examined at the microscopic level. SO2 is adsorbed on the pore surface through two types of hydrogen bonds, either between O of SO2 with the closest H of the triazole 5-membred ring or between O of SO2 with the hydrogen of the amino group. For H2S inside the pores, the principal interactions between H2S and surface pores are due to a relatively strong hydrogen bonds established between the nitrogens of the organic part of MOFs and H2S. Also, we found that these interactions depend on the orientation of SO2/H2S inside the pores. Moreover, we have studied the influence of the presence of water and CO2 on H2S and SO2 capture by the ZTF MOF. The present GCMC simulations reveal that the addition of H2O molecules at low pressure leads to an enhancement of the H2S adsorption, in agreement with experimental findings. However, the presence of water molecules decreases the adsorption of SO2 irrespective of the pressure used. Besides, SO2 adsorption is increased in the presence of a small number of CO2 molecules, whereas the presence of carbon dioxide in ZTF pores has an unfavorable effect on the capture of H2S.

In silico design of a new Zn-triazole based metal-organic framework for CO2 and H2O adsorption.

In search for future good adsorbents for CO2 capture, a nitrogen-rich triazole-type Metal-Organic Framework (MOF) is proposed based on the rational design and theoretical molecular simulations. The structure of the proposed MOF, named Zinc Triazolate based Framework (ZTF), is obtained by replacing the amine-organic linker of MAF-66 by a triazole, and its structural parameters are deduced. We used grand-canonical Monte Carlo (GCMC) simulations based on generic classical force fields to correctly predict the adsorption isotherms of CO2 and H2O. For water adsorption in MAF-66 and ZTF, simulations revealed that the strong hydrogen bonding interactions of water with the N atoms of triazole rings of the frameworks are the main driving forces for the high adsorption uptake of water. We also show that the proposed ZTF porous material exhibits exceptional high CO2 uptake capacity at low pressure, better than MAF-66. Moreover, the nature of the interactions between CO2 and the MAF-66 and ZTF surface cavities was examined at the microscopic level. Computations show that the interactions occur at two different sites, consisting of Lewis acid-Lewis base interactions and hydrogen bonding, together with obvious electrostatic interactions. In addition, we investigated the influence of the presence of H2O molecules on the CO2 adsorption on the ZTF MOF. GCMC simulations reveal that the addition of H2O molecules leads to an enhancement of the CO2 adsorption at very low pressures but a reduction of this CO2 adsorption at higher pressures.

[Right ventricular function after a first episode of pulmonary embolism: Contribution of longitudinal 2D strain]. / Fonction ventriculaire droite après un premier épisode d'embolie pulmonaire : apport du strain 2D.

BACKGROUND: Analysis of right ventricular (RV) function during the acute phase of pulmonary embolism (PE) was widely reported in the literature. However, few studies analysed its function long term after the acute phase. Our aim was to evaluate the RV function long term after a first episode of PE. METHODS: In this study, we compared echocardiographic parameters of right ventricular function in 25 patients with a first episode of non-severe PE for more than six months with 25 healthy controls subject. RESULTS: In the study of RV function, we noted that the mean values of the standard parameters were significantly lower in the EP group compared to the control group but their values remained within the normal range. The global RV longitudinal strain had a mean value lower than the control group statistically significant (-21±4,8% vs. -25±2,4%; P=0,28). The longitudinal strain of the free wall of the RV was altered in the EP group, however, there was no significant difference between the EP group and the control group (-19,4±16% vs. -24±17%; P=0,28). CONCLUSION: This study has shown that there is a systolic dysfunction late after a first episode of PE and this despite the absence of the symptoms and pulmonary hypertension.

Insights on the interaction of Zn2+ cation with triazoles: Structures, bonding, electronic excitation and applications.

At present, we investigate the structures, the stability, the bonding and the spectroscopy of the Zn2+-triazole complexes (Zn2+-Tz), which are subunits of triazolate based porous materials and Zn-enzymes. This theoretical work is performed using ab initio methods and density functional theory (DFT) where dispersion correction is included. Through these benchmarks, we establish the ability and reliability of M05-2X+D3 and PBE0+D3 functionals for the correct description of Zn2+-Tz bond since these DFTs lead to close agreement with post Hartree-Fock methods. Therefore, M05-2X+D3 and PBE0+D3 functionals are recommended for the characterization of larger organometallic complexes formed by Zn and N-rich linkers. For Zn2+-Tz, we found two stable σ-type complexes: (i) a planar structure where Zn2+ links to unprotonated nitrogen and (ii) an out-of-plane cluster where carbon interacts with Zn2+. The most stable isomers consist on a coordinated covalent bond between the lone pair of unprotonated nitrogen and the vacant 4s orbital of Zn2+. The roles of covalent interactions within these complexes are discussed after vibrational, NBO, NPA charges and orbital analyses. The bonding is dominated by charge transfer from Zn2+ to Tz and intramolecular charge transfer, which plays a vital role for the catalytic activity of these complexes. These findings are important to understand, at the microscopic level, the structure and the bonding within triazolate based macromolecular porous materials and Zn-enzymes.

Unruptured multiple intracranial aneurysms associated with Behçet's disease.

Behçet's disease is a systemic inflammatory disorder with a wide variety of cardiovascular complications. Intracranial aneurysm is extremely rare. Herein, we are presenting a 41-year-old male with Behçet's disease and a headache. A cranial computed tomography scan angiography showed unruptured right supra cavernus internal carotid aneurysm and right sylvian artery aneurysm. Treatment consisted of prednisone and azathioprine. Control imaging showed no aneurysm.

A novel LKB1 isoform enhances AMPK metabolic activity and displays oncogenic properties.

The LKB1 tumor suppressor gene encodes a master kinase that coordinates the regulation of energetic metabolism and cell polarity. We now report the identification of a novel isoform of LKB1 (named ΔN-LKB1) that is generated through alternative transcription and internal initiation of translation of the LKB1 mRNA. The ΔN-LKB1 protein lacks the N-terminal region and a portion of the kinase domain. Although ΔN-LKB1 is catalytically inactive, it potentiates the stimulating effect of LKB1 on the AMP-activated protein kinase (AMPK) metabolic sensor through a direct interaction with the regulatory autoinhibitory domain of AMPK. In contrast, ΔN-LKB1 negatively interferes with the LKB1 polarizing activity. Finally, combining in vitro and in vivo approaches, we showed that ΔN-LKB1 has an intrinsic oncogenic property. ΔN-LKB1 is expressed solely in the lung cancer cell line, NCI-H460. Silencing of ΔN-LKB1 decreased the survival of NCI-H460 cells and inhibited their tumorigenicity when engrafted in nude mice. In conclusion, we have identified a novel LKB1 isoform that enhances the LKB1-controlled AMPK metabolic activity but inhibits LKB1-induced polarizing activity. Both the LKB1 tumor suppressor gene and the oncogene ΔN-LKB1 are expressed from the same locus and this may account for some of the paradoxical effects of LKB1 during tumorigenesis.

AOTF Raman spectrometer for remote detection of explosives.

A spectrometer based on acousto-optic tunable filters is developed for use in measuring Raman spectra as part of a detection system that is low-cost, reliable, and field-portable. The system is coupled with a fiber optic bundle to carry the excitation laser light to the sample and to collect the Raman scattered light. Spectra of the explosives trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX) and nitroguanidine (NQ) were obtained in very short times and are in good agreement with those taken with conventional Fourier transform Raman spectrometers. Spectra of mixtures of explosives were also obtained and show no overlap of their characteristic Raman bands.