2,669 research outputs found
Addition of Di(trimethylsilyl) Phosphite to Schiff Bases of 2,5-Diformylfuran
A series of 2,5-Furanyl-bis-(aminomethylphosphonic Acids) has been synthesized by the addition of di(trimethylsilyl) phosphite to azomethine bond of achiral Schiff bases derved from 2,5-diformylfuran. The stereochemical aspect of this reaction has been studied and compared with the behaviour of achiral terephthalic Schiff bases in similar reaction. Whereas, addition to achiral terephthalic Schiff bases was found to be highly stereoselective, the analogous reaction with achiral 2,5-diformylfuran Schiff bases was stereoselective exclusively in the case when the substituent is benzyl.N/
Persistent Currents in Twisted Tori Made of Chiral Nanotubes
Mesoscopic metal rings can carry persistent currents driven by a constant
magnetic field. The geometrical structure of a toroidal carbon nanotube
can be characterized by four independent parameters. We derive the
formula for persistent currents driven by a constant Bohm-Aharonov type
of field perpendicular to the plane of the torus. The dependencies of the
currents on the chirality, twist and circumference of the torus are discussed
Constrained clustering with a complex cluster structure
In this contribution we present a novel constrained clustering method, Constrained clustering with a complex cluster structure (C4s), which incorporates equivalence constraints, both positive and negative, as the background information. C4s is capable of discovering groups of arbitrary structure, e.g. with multi-modal distribution, since at the initial stage the equivalence classes of elements generated by the positive constraints are split into smaller parts. This provides a detailed description of elements, which are in positive equivalence relation. In order to enable an automatic detection of the number of groups, the cross-entropy clustering is applied for each partitioning process. Experiments show that the proposed method achieves significantly better results than previous constrained clustering approaches. The advantage of our algorithm increases when we are focusing on finding partitions with complex structure of clusters
2-year follow-up of Lung transplantation as a treatment of Hereditary hemorrhagic telangiectasia (Osler–Weber–Rendu disease) – a case report
Hemorrhagic telangiectasia (HHT) is a disease of initially mild course - manifesting with recurrent nosebleeds and increasedfatigue. Nevertheless, its progression can deteriorate patient’s health. Solid organ transplantation becomes the only therapeuticoption to save a life.Case series describes a 19-year-old female patient who was diagnosed with HHT and qualified for lung transplantation. Shemet the Curacao criteria for HHT (¾). Her health deteriorated significantly to the point of the referral to Department of Cardiac,Vascular and Endovascular Surgery and Transplantology. Due to her condition, she was qualified for lung transplantation as onediagnosed with pulmonary arteriovenous malformations and then transplanted at the age of 17. A direct postoperative period wascomplicated by HSV2 infection of the wound. 18 months after the procedure, the patient underwent acute cholangitis. The presenceof portal and systemic fistulas was noted and the final diagnosis of HHT was made. Despite the fact that proper diagnosiswas made posttransplant, it was a good treatment. The patient is currently 2 years after the lung transplantation and feels good.Lung transplantation is a viable therapeutic option for patients with HHT as there are reports of other patients who have benefitedfrom lung transplantation after other therapeutic options were exhausted
Structure and properties of slow-resorbing nanofibers obtained by (co-axial) electrospinning as tissue scaffolds in regenerative medicine
With the rapid advancement of regenerative medicine technologies, there is an urgent need for the development of new, cell-friendly techniques for obtaining nanofibers—the raw material for an artificial extracellular matrix production. We investigated the structure and properties of PCL10 nanofibers, PCL5/PCL10 core-shell type nanofibers, as well as PCL5/PCLAg nanofibres prepared by electrospinning. For the production of the fiber variants, a 5–10% solution of polycaprolactone (PCL) (Mw = 70,000–90,000), dissolved in a mixture of formic acid and acetic acid at a ratio of 70:30 m/m was used. In order to obtain fibers containing PCLAg 1% of silver nanoparticles was added. The electrospin was conducted using the above-described solutions at the electrostatic field. The subsequent bio-analysis shows that synthesis of core-shell nanofibers PCL5/PCL10, and the silver-doped variant nanofiber core shell PCL5/PCLAg, by using organic acids as solvents, is a robust technique. Furthermore, the incorporation of silver nanoparticles into PCL5/PCLAg makes such nanofibers toxic to model microbes without compromising its biocompatibility. Nanofibers obtained such way may then be used in regenerative medicine, for the preparation of extracellular scaffolds: (i) for controlled bone regeneration due to the long decay time of the PCL, (ii) as bioscaffolds for generation of other types of artificial tissues, (iii) and as carriers of nanocapsules for local drug delivery. Furthermore, the used solvents are significantly less toxic than the solvents for polycaprolactone currently commonly used in electrospin, like for example chloroform (CHCl3), methanol (CH3OH), dimethylformamide (C3H7NO) or tetrahydrofuran (C4H8O), hence the presented here electrospin technique may allow for the production of multilayer nanofibres more suitable for the use in medical field
Social Security, Labour Market and Restructuring: Current Situation and Expected Outcomes of Reforms
The paper focuses on the social safety nets in Russian Federation and Ukraine in the view of changes on the labour market since the beginning of economic transition. We showed that many past phenomena (e.g. restructuring of the economy, wage and pension arrears, new groups at-risk-of-poverty, demographic transition) caused a need to change an old type social safety net (SSN) into the new one, better adapted to emerging more liberal economy problems. Additionally, we analysed some gender specific issues related to social security that are caused mainly by inequalities in the labour market. Differences of earnings between men and women in Russia caused by sector segregation account for seem to be more important than the gap between gender earnings attributed to the position. In Ukraine the main contributors to gross gender differential of log earnings (that equals to 32%) explained by our model are sector segregation and occupation. We also pointed out to future policy challenges in the area of social security systems in both countries. The retirement reforms introduced recently are a step in the right direction, although their impact will not be felt for a number of years. Other reforms, with more immediate results, are necessary. Social safety nets should be made more efficient and social benefits should be better targeted.Social safety net, labour market, transitional economies
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