Spin Dependent Tunneling in FM|semiconductor|FM structures

Here we show that ordinary band structure codes can be used to understand the mechanisms of coherent spin-injection at interfaces between ferromagnets and semiconductors. This approach allows the screening of different material combinations for properties useful for obtaining high tunneling magnetoresistance (TMR). We used the Vienna Ab-initio Simulation Code (VASP) to calculate the wave function character of each band in periodic epitaxial Fe(100)|GaAs(100) and Fe(100)|ZnSe(100) structures. It is shown that Fe wave functions of different symmetry near Fermi energy decay differently in the GaAs and ZnSe.Comment: Accepted for publication in MMM'05 Proceedings. 7 pages, 5 figure

Rational design and dynamics of self-propelled colloidal bead chains: from rotators to flagella

The quest for designing new self-propelled colloids is fuelled by the demand for simple experimental models to study the collective behaviour of their more complex natural counterparts. Most synthetic self-propelled particles move by converting the input energy into translational motion. In this work we address the question if simple self-propelled spheres can assemble into more complex structures that exhibit rotational motion, possibly coupled with translational motion as in flagella. We exploit a combination of induced dipolar interactions and a bonding step to create permanent linear bead chains, composed of self-propelled Janus spheres, with a well-controlled internal structure. Next, we study how flexibility between individual swimmers in a chain can affect its swimming behaviour. Permanent rigid chains showed only active rotational or spinning motion, whereas longer semi-flexible chains showed both translational and rotational motion resembling flagella like-motion, in the presence of the fuel. Moreover, we are able to reproduce our experimental results using numerical calculations with a minimal model, which includes full hydrodynamic interactions with the fluid. Our method is general and opens a new way to design novel self-propelled colloids with complex swimming behaviours, using different complex starting building blocks in combination with the flexibility between them.Comment: 27 pages, 10 figure

Fingolimod for the treatment of neurological diseases—state of play and future perspectives

Sphingolipids are a fascinating class of signaling molecules derived from the membrane lipid sphingomyelin. They show abundant expression in the brain. Complex sphingolipids such as glycosphingolipids (gangliosides and cerebrosides) regulate vesicular transport and lysosomal degradation and their dysregulation can lead to storage diseases with a neurological phenotype. More recently, simple sphingolipids such ceramide, sphingosine and sphingosine 1-phosphate (S1P) were discovered to signal in response to many extracellular stimuli. Forming an intricate signaling network, the balance of these readily interchangeable mediators is decisive for cell fate under stressful conditions.The immunomodulator fingolimod is the prodrug of an S1P receptor agonist. Following receptor activation, the drug leads to downregulation of the S1P1 receptor with the consequence of functional antagonism. Being the first drug to modulate the sphingolipid signaling pathway, it was marketed in 2010 for the treatment of multiple sclerosis (MS). At that time, immunomodulation was widely accepted as the key mechanism of fingolimod's efficacy in MS.But given the excellent passage of this lipophilic compound into the brain and its massive brain accumulation as well as the abundant expression of S1P receptors on brain cells, it is conceivable that fingolimod also affects brain cells directly. Indeed, a seminal study showed that the protective effect of fingolimod in experimental autoimmune encephalitis (EAE), a murine MS model, is lost in mice lacking the S1P1 receptor on astrocytes, arguing for a specific role of astrocytic S1P signaling in multiple sclerosis. In this review, we discuss the role of sphingolipid mediators and their metabolizing enzymes in neurologic diseases and putative therapeutic strategies arising thereof

Моделювання еволюції надпотужних конвективних утворень над Кримом під час проходження смерчів

Предметом даного дослідження були умови формування осередків надпотужних вертикальних рухів, сильних вихорів та надпотужних конвективних утворень під час проходження смерчів над центральною частиною Криму 22 липня 2002 р. Тривимірні прогностичні мікрофізичні моделі фронтальних систем хмар з урахуванням та без урахування складного рельєфу, розроблені в УкрНДГМІ, було адаптовано до умов розвитку хмарності в екстремальних умовах розвитку смерчів. Проведено декілька серій чисельних експериментів для пошуку ключових параметрів, які спричиняли та визначали характер розвитку вихрових утворень і процесів, що їх супроводжують.Предметом исследования в работе были условия формирования ячеек сверхмощных вертикальных движений, сильных вихрей, сверхмощных конвективных образований во время прохождения смерчей над центральной частью Крыма 22 июля 2002 года. Трехмерные прогностические микрофизические модели с учетом и без учета орографии, разработанные в УкрНИГМИ, были адаптированы для условий эволюции фронтальных облачных систем в экстремальных условиях развития смерчей. Проведено несколько серий численных экспериментов с целью поиска ключевых параметров, определяющих характер развития вихревых образований и сопровождающих их явлений

Які адміністративні суди потрібні Україні?

Исследуется вопрос целесообразности создания в Украине системы административных судов, анализируется эффективность их деятельности и улучшение с их созданием состояния защиты прав граждан и юридических лиц в отношениях с государственными органами, а также влияние на это норм Кодекса административного судопроизводства.In article it is researched of question of expedience of creation in Ukraine of the system of administrative courts, efficiency of their activity and improvement is analyzed with their creation of the state of defence of rights for citizens and artificial persons in relationships with public organs, and also influence on it of norms of Code of the administrative legal proceeding

Role of Shape in Particle-Lipid Membrane Interactions: From Surfing to Full Engulfment

Understanding and manipulating the interactions between foreign bodies and cell membranes during endo- and phagocytosis is of paramount importance, not only for the fate of living cells but also for numerous biomedical applications. This study aims to elucidate the role of variables such as anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength in this essential process using a minimal experimental biomimetic system comprising giant unilamellar vesicles and rod-like particles with different curvatures and aspect ratios. We find that the particle wrapping process is dictated by the balance between the elastic free energy penalty and adhesion free energy gain, leading to two distinct engulfment pathways, tip-first and side-first, emphasizing the significance of the particle orientation in determining the pathway. Moreover, our experimental results are consistent with theoretical predictions in a state diagram, showcasing how to control the wrapping pathway from surfing to partial to complete wrapping by the interplay between membrane tension and adhesive strength. At moderate particle concentrations, we observed the formation of rod clusters, which exhibited cooperative and sequential wrapping. Our study contributes to a comprehensive understanding of the mechanistic intricacies of endocytosis by highlighting how the interplay between the anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength can influence the engulfment pathway

Role of Shape in Particle-Lipid Membrane Interactions:From Surfing to Full Engulfment

Understanding and manipulating the interactions between foreign bodies and cell membranes during endo- and phagocytosis is of paramount importance, not only for the fate of living cells but also for numerous biomedical applications. This study aims to elucidate the role of variables such as anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength in this essential process using a minimal experimental biomimetic system comprising giant unilamellar vesicles and rod-like particles with different curvatures and aspect ratios. We find that the particle wrapping process is dictated by the balance between the elastic free energy penalty and adhesion free energy gain, leading to two distinct engulfment pathways, tip-first and side-first, emphasizing the significance of the particle orientation in determining the pathway. Moreover, our experimental results are consistent with theoretical predictions in a state diagram, showcasing how to control the wrapping pathway from surfing to partial to complete wrapping by the interplay between membrane tension and adhesive strength. At moderate particle concentrations, we observed the formation of rod clusters, which exhibited cooperative and sequential wrapping. Our study contributes to a comprehensive understanding of the mechanistic intricacies of endocytosis by highlighting how the interplay between the anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength can influence the engulfment pathway.</p

Role of Shape in Particle-Lipid Membrane Interactions: From Surfing to Full Engulfment

Understanding and manipulating the interactions between foreign bodies and cell membranes during endo- and phagocytosis is of paramount importance, not only for the fate of living cells but also for numerous biomedical applications. This study aims to elucidate the role of variables such as anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength in this essential process using a minimal experimental biomimetic system comprising giant unilamellar vesicles and rod-like particles with different curvatures and aspect ratios. We find that the particle wrapping process is dictated by the balance between the elastic free energy penalty and adhesion free energy gain, leading to two distinct engulfment pathways, tip-first and side-first, emphasizing the significance of the particle orientation in determining the pathway. Moreover, our experimental results are consistent with theoretical predictions in a state diagram, showcasing how to control the wrapping pathway from surfing to partial to complete wrapping by the interplay between membrane tension and adhesive strength. At moderate particle concentrations, we observed the formation of rod clusters, which exhibited cooperative and sequential wrapping. Our study contributes to a comprehensive understanding of the mechanistic intricacies of endocytosis by highlighting how the interplay between the anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength can influence the engulfment pathway