Incarcerated vermiform appendix in a left-sided inguinal hernia

We report here of a patient with an incarcerated vermiform appendix occurring in a left-sided indirect inguinal hernia. Occasionally, appendices are found in a hernial sac; however, the finding of an incarcerated vermiform appendix in an inguinal hernia on the left side is very unusual and has only been previously described once. The patient suffering this rare entity underwent appendectomy and repair of the hernia and experienced an uneventful postoperative recovery. The possibility of the presence of a situs inversus, or malrotation, as an underlying cause for the observed pathology was excluded by x-ray examinatio

Dithiinmaleimide Functionalized ET Derivatives: Syntheses, Characterization and X-ray Structure

Dithiinmaleimide (ethylenedithio)tetrathiafulvalene (1) and N-phenyldithiinmaleimide (ethylenedithio)tetrathiafulvalene (2) have been synthesized from bis(tetraethylammonium)bis(ethylenedithiotetrathiafulvalenyldithiolato)-zincate (3) in high yields. Their electrochemical properties were investigated by cyclic voltammetry (CV) measurements which show two reversible redox potentials of the tetrathiafulvalene (TTF) moiety and an irreversible reduction potential of the maleimide ring. The X-ray structure of 1 shows close S···S contacts in the range of the van der Waals radii (3.6 Å) and hydrogen bonds between the maleimide unite

Structure and Magnetic Properties of the Radical Cation Salt of a TTF-based NiII Complex

Chemical oxidation of a TTF-based NiII complex with I2 produces the corresponding radical cation salt 1, [Ni2Cl2(L)2](I3)2(I5)2(I2)(H2O)2(C4H8O)3, (L=4,5-bis(2-pyridylmethylsulfanyl)-4',5'-ethylenedithiotetrathiafulvalene). The results of magnetic susceptibility measurements show the occurrence of intramolecular magnetic exchange interactions in 1. The lack of close S···S contacts, confirmed by crystal structure analysis, results in an insulating behavio

Synthesis beyond the redox-active tetrathiafulvalene (TTF) molecule: From a topological control in TTF based macrocycles, towards functional chemical systems

Date du colloque&nbsp;: 05/2009</p

Numerical Study of a Mixed Ising Ferrimagnetic System

We present a study of a classical ferrimagnetic model on a square lattice in which the two interpenetrating square sublattices have spins one-half and one. This model is relevant for understanding bimetallic molecular ferrimagnets that are currently being synthesized by several experimental groups. We perform exact ground-state calculations for the model and employ Monte Carlo and numerical transfer-matrix techniques to obtain the finite-temperature phase diagram for both the transition and compensation temperatures. When only nearest-neighbor interactions are included, our nonperturbative results indicate no compensation point or tricritical point at finite temperature, which contradicts earlier results obtained with mean-field analysis.Comment: Figures can be obtained by request to [email protected] or [email protected]

Forces from periodic charging of adsorbed molecules

In a recent publication [N. Kocic et al., Nano Lett. 15, 4406 (2015)], it was shown that gating of molecular levels in the field of an oscillating tip of an atomic force microscope can enable a periodic charging of individual molecules synchronized to the tip's oscillatory motion. Here we discuss further implications of such measurements, namely, how the force difference associated with the singleelectron charging manifests itself in atomic force microscopy images and how it can be detected as a function of tip-sample distance. Moreover, we discuss how the critical voltage for the chargestate transition depends on distance and how that relates to the local contact potential difference. These measurements allow also for an estimate of the absolute tip-sample distance

Efficient Palladium-Catalyzed Cyclotrimeriza- tion of Arynes: Synthesis of Triphenylenes**

Over the last 15 years much effort has been devoted to the preparation and characterization of transition metal complexes of arynes. [1] Parallel studies on the reactivity of these complexesÐparticularly those of Ti, Zr, As part of a project aimed at the development of new reactions of arynes promoted by metal complexes, here we report on the metal-mediated cyclotrimerization of arynes. These preliminary results show that the reaction proceeds in the presence of catalytic amounts of metal and that it has great potential for the preparation of triphenylenes, which are found at the core of many discotic liquid crystals [9] An example of the formation of triphenylene as side product of a palladium-catalyzed domino reaction has also been reported. [10] However, to the best of our knowledge, efficient preparation of triphenylenes by metalcatalyzed reaction of arynes is without precedent. Development of a catalytic procedure for the trimerization of arynes requires careful selection of the catalyst and the method for generation of the aryne. The catalyst was chosen from among the various metal systems used for trimerization of alkynes; suitable candidates contained metals such as Ni, Co, Pd, and Pt. We decided to carry out the first trials with palladium complexes because they are easy to handle and in general stable. Among the many procedures available for the generation of arynes [9] S

Repair of Parastomal Hernias with Biologic Grafts: A Systematic Review

Contains fulltext : 98303.pdf (publisher's version ) (Open Access)BACKGROUND: Biologic grafts are increasingly used instead of synthetic mesh for parastomal hernia repair due to concerns of synthetic mesh-related complications. This systematic review was designed to evaluate the use of these collagen-based scaffolds for the repair of parastomal hernias. METHODS: Studies were retrieved after searching the electronic databases MEDLINE, EMBASE and Cochrane CENTRAL. The search terms 'paracolostomy', 'paraileostomy', 'parastomal', 'colostomy', 'ileostomy', 'hernia', 'defect', 'closure', 'repair' and 'reconstruction' were used. Selection of studies and assessment of methodological quality were performed with a modified MINORS index. All reports on repair of parastomal hernias using a collagen-based biologic scaffold to reinforce or bridge the defect were included. Outcomes were recurrence rate, mortality and morbidity. RESULTS: Four retrospective studies with a combined enrolment of 57 patients were included. Recurrence occurred in 15.7% (95% confidence interval [CI] 7.8-25.9) of patients and wound-related complications in 26.2% (95% CI 14.7-39.5). No mortality or graft infections were reported. CONCLUSIONS: The use of reinforcing or bridging biologic grafts during parastomal hernia repair results in acceptable rates of recurrence and complications. However, given the similar rates of recurrence and complications achieved using synthetic mesh in this scenario, the evidence does not support use of biologic grafts

Theoretical investigation of the electronic structure of Fe(II) complexes at spin-state transitions

The electronic structure relevant to low spin (LS)high spin (HS) transitions in Fe(II) coordination compounds with a FeN6 core are studied. The selected [Fe(tz)6]2+(1) (tz=1H-tetrazole), [Fe(bipy)3]2+(2) (bipy=2,2’-bipyridine) and [Fe(terpy)2]2+ (3) (terpy=2,2’:6’,2’’-terpyridine) complexes have been actively studied experimentally, and with their respective mono-, bi-, and tridentate ligands, they constitute a comprehensive set for theoretical case studies. The methods in this work include density functional theory (DFT), time-dependent DFT (TD-DFT) and multiconfigurational second order perturbation theory (CASPT2). We determine the structural parameters as well as the energy splitting of the LS-HS states (ΔEHL) applying the above methods, and comparing their performance. We also determine the potential energy curves representing the ground and low-energy excited singlet, triplet, and quintet d6 states along the mode(s) that connect the LS and HS states. The results indicate that while DFT is well suited for the prediction of structural parameters, an accurate multiconfigurational approach is essential for the quantitative determination of ΔEHL. In addition, a good qualitative agreement is found between the TD-DFT and CASPT2 potential energy curves. Although the TD-DFT results might differ in some respect (in our case, we found a discrepancy at the triplet states), our results suggest that this approach, with due care, is very promising as an alternative for the very expensive CASPT2 method. Finally, the two dimensional (2D) potential energy surfaces above the plane spanned by the two relevant configuration coordinates in [Fe(terpy)2]2+ were computed both at the DFT and CASPT2 levels. These 2D surfaces indicate that the singlet-triplet and triplet-quintet states are separated along different coordinates, i.e. different vibration modes. Our results confirm that in contrast to the case of complexes with mono- and bidentate ligands, the singlet-quintet transitions in [Fe(terpy)2]2+ cannot be described using a single configuration coordinate

Time-resolved single-crystal X-ray crystallography

In this chapter the development of time-resolved crystallography is traced from its beginnings more than 30 years ago. The importance of being able to “watch” chemical processes as they occur rather than just being limited to three-dimensional pictures of the reactant and final product is emphasised, and time-resolved crystallography provides the opportunity to bring the dimension of time into the crystallographic experiment. The technique has evolved in time with developments in technology: synchrotron radiation, cryoscopic techniques, tuneable lasers, increased computing power and vastly improved X-ray detectors. The shorter the lifetime of the species being studied, the more complex is the experiment. The chapter focusses on the results of solid-state reactions that are activated by light, since this process does not require the addition of a reagent to the crystalline material and the single-crystalline nature of the solid may be preserved. Because of this photoactivation, time-resolved crystallography is often described as “photocrystallography”. The initial photocrystallographic studies were carried out on molecular complexes that either underwent irreversible photoactivated processes where the conversion took hours or days. Structural snapshots were taken during the process. Materials that achieved a metastable state under photoactivation and the excited (metastable) state had a long enough lifetime for the data from the crystal to be collected and the structure solved. For systems with shorter lifetimes, the first time-resolved results were obtained for macromolecular structures, where pulsed lasers were used to pump up the short lifetime excited state species and their structures were probed by using synchronised X-ray pulses from a high-intensity source. Developments in molecular crystallography soon followed, initially with monochromatic X-ray radiation, and pump-probe techniques were used to establish the structures of photoactivated molecules with lifetimes in the micro- to millisecond range. For molecules with even shorter lifetimes in the sub-microsecond range, Laue diffraction methods (rather than using monochromatic radiation) were employed to speed up the data collections and reduce crystal damage. Future developments in time-resolved crystallography are likely to involve the use of XFELs to complete “single-shot” time-resolved diffraction studies that are already proving successful in the macromolecular crystallographic field.</p