Effect of Boundary Conditions on the Behavior of Stiffened and Un-Stiffened Cylindrical Shells

The effect of boundary conditions is very important in the analysis of cylindrical shells, and is rarely studied in the literature due to its difficult experimental simulation. For large structures such as shell roofs, the type of boundary supports is among the major factors that can minimize the stresses and deflections. In this study, experimental and numerical investigations of the effect of different boundary supports for stiffened and un-stiffened cylindrical shells were conducted. Two different models of the stiffened and un-stiffened cylindrical shells with different boundary conditions, “pinned and with rigid diaphragms”, were studied. It was shown that by using rigid diaphragms for cylindrical shells, the deflections are minimized by 80%, and by (45–50) % for the stiffened cylindrical shells. From the experimental investigations and the numerical results obtained, the efficiency of the proposed boundary support types for cylindrical shells is confirmed, which can result in economic benefits

Unique challenges accompany thick-shell CdSe/nCdS (n \u3e 10) nanocrystal synthesis

Thick-shell CdSe/nCdS (n \u3e10) nanocrystals were recently reported that show remarkably suppressed fluorescence intermittency or blinking at the single-particle level as well as slow rates of Auger decay. Unfortunately, whereas CdSe/nCdS nanocrystal synthesis is well-developed up to n \u3c 6 CdS monolayers (MLs), reproducible syntheses for n \u3e 10 MLs are less understood. Known procedures sometimes result in homogeneous CdS nucleation instead of heterogeneous, epitaxial CdS nucleation on CdSe, leading to broad and multimodal particle size distributions. Critically, obtained core/shell sizes are often below those desired. This article describes synthetic conditions specific to thick-shell growth (n\u3e 10 and n\u3e 20 MLs) on both small (sub2 nm) and large (\u3e4.5 nm) CdSe cores. We find added secondary amine and low concentration of CdSe cores and molecular precursors give desired core/shell sizes. Amine-induced, partial etching of CdSe cores results in apparent shell-thicknesses slightly beyond those desired, especially for very-thick shells (n \u3e20 MLs). Thermal ripening and fast precursor injection lead to undesired homogeneous CdS nucleation and incomplete shell growth. Core/shells derived from small CdSe (1.9 nm) have longer PL lifetimes and more pronounced blinking at single-particle level compared with those derived from large CdSe (4.7 nm). We expect our new synthetic approach will lead to a larger throughput of these materials, increasing their availability for fundamental studies and applications

ALK1 signalling analysis identifies angiogenesis related genes and reveals disparity between TGF-β and constitutively active receptor induced gene expression

BACKGROUND: TGF-β1 is an important angiogenic factor involved in the different aspects of angiogenesis and vessel maintenance. TGF-β signalling is mediated by the TβRII/ALK5 receptor complex activating the Smad2/Smad3 pathway. In endothelial cells TGF-β utilizes a second type I receptor, ALK1, activating the Smad1/Smad5 pathway. Consequently, a perturbance of ALK1, ALK5 or TβRII activity leads to vascular defects. Mutations in ALK1 cause the vascular disorder hereditary hemorrhagic telangiectasia (HHT). METHODS: The identification of ALK1 and not ALK5 regulated genes in endothelial cells, might help to better understand the development of HHT. Therefore, the human microvascular endothelial cell line HMEC-1 was infected with a recombinant constitutively active ALK1 adenovirus, and gene expression was studied by using gene arrays and quantitative real-time PCR analysis. RESULTS: After 24 hours, 34 genes were identified to be up-regulated by ALK1 signalling. Analysing ALK1 regulated gene expression after 4 hours revealed 13 genes to be up- and 2 to be down-regulated. Several of these genes, including IL-8, ET-1, ID1, HPTPη and TEAD4 are reported to be involved in angiogenesis. Evaluation of ALK1 regulated gene expression in different human endothelial cell types was not in complete agreement. Further on, disparity between constitutively active ALK1 and TGF-β1 induced gene expression in HMEC-1 cells and primary HUVECs was observed. CONCLUSION: Gene array analysis identified 49 genes to be regulated by ALK1 signalling and at least 14 genes are reported to be involved in angiogenesis. There was substantial agreement between the gene array and quantitative real-time PCR data. The angiogenesis related genes might be potential HHT modifier genes. In addition, the results suggest endothelial cell type specific ALK1 and TGF-β signalling

Resonant enhanced diffusion in time dependent flow

Explicit examples of scalar enhanced diffusion due to resonances between different transport mechanisms are presented. Their signature is provided by the sharp and narrow peaks observed in the effective diffusivity coefficients and, in the absence of molecular diffusion, by anomalous transport. For the time-dependent flow considered here, resonances arise between their oscillations in time and either molecular diffusion or a mean flow. The effective diffusivities are calculated using multiscale techniques.Comment: 18 latex pages, 11 figure

THE SCOPE AND CONSEQUENCES OF ILLEGAL AMBER EXTRACTION ON LANDS OF ZHYTOMYR RDFH

Проведено об'єктивне оцінювання масштабів і наслідків ушкоджень земель Житомирського ОУЛМГ внаслідок незаконного видобутку бурштину. Ділянки лісових насаджень, що потребують рекультивації, виявлено на території трьох державних підприємств та семи лісництв. Встановлено, що загальна площа земель Житомирського ОУЛМГ, що потребують рекультивації, становить 369, 45 га. Найбільше порушених площ (336,60 га) розміщено на території ДП "Білокоровицьке ЛГ", ДП "Олевське ЛГ" (30,70 га) і ДП "Словечанське ЛГ" (2,15 га). Здійснено аналіз основних типів порушень ґрунту та лісових ценозів. За результатами аналізу лісівничо-таксаційних показників пошкоджених насаджень визначено найпоширеніші типи лісорослинних умов, типи лісу, видовий склад та вікову структуру. Встановлено, що внаслідок незаконного видобутку пошкоджено та знищено низку територій, що мають статус заказників місцевого та загальнодержавного значення.На території кварталів 20 і 21 Поясківського лісівництва, кварталу 27 Можарівського лісництва та кварталу 29 Сирницького лісництва закладено тимчасові пробні площі. Перспектива подальших досліджень полягає у встановленні особливостей та шляхів стимулювання природного поновлення рослинності на деградованих внаслідок незаконного видобутку територіях, дослідженні впливу абіотичних екологічних чинників на процеси поновлення рослинного покриву.Проведена объективная оценка масштабов и последствий повреждений земель Житомирского ОУЛОХ в результате незаконной добычи янтаря. Участки лесных насаждений, требующие рекультивации, обнаружены на территории трех государственных предприятий и семи лесничеств. Установлено, что общая площадь земель Житомирского ОУЛОХ, требующих рекультивации, составляет 369,45 га. Большинство нарушенных площадей (336,60 га) находится на территории ГП "Белокоровецкое ЛГ", ГП "Олевское ЛГ" (30,70 га) и ГП "Словечанское ЛГ" (2,15 га). Осуществлен анализ основных типов нарушений почвы и лесных ценозов. По результатам анализа лесоводственно-таксационных показателей поврежденных насаждений определены наиболее распространенные типы лесорастительных условий, типы леса, видовой состав и возрастная структура. Установлено, что в результате незаконной добычи повреждено и уничтожено ряд территорий, имеющих статус заказников местного и общегосударственного значения. На территории кварталов 20, 21 Пояскивского лесничества, квартала 27 Можаровского лесничества и квартала 29 Сырницкого лесничества заложены временные пробные площади. Перспективы дальнейших исследований заключаются в установлении особенностей и путей стимулировании естественного возобновления растительности на деградированных в результате незаконной добычи территориях, исследовании влияния абиотических экологических факторов на процессы обновления растительного покрова.The problem of damage to forestry in Ukraine has become acute due to the unauthorized extraction of amber today. The issues of reclamation and dendro-reclamation of such lands are new and little-studied. The research used general sciences methods (analysis, synthesis, observation, generalization) and special research methods: visual (determining the general condition of plants and damage to the territory), agrochemical (determination of basic nutrients and soil acidity) and mathematical statistics (processing of experimental data with using computer programs). An objective assessment of the scale and damage consequences to the lands of Zhytomyr Region Department of Forestry and Hunting Economy as a result of the illegal amber mining has been carried out. The areas of forest plantations requiring reclamation on the territory of three state enterprises and seven forestry enterprises were identified. The total area of land requiring reclamation is 369.45 hectares. Most of the disturbed areas (336.60 ha) located on the territory of State Enterprise Belokorovyts'ke FE, State Enterprise Olevske FE (30.70 ha) and Subsidiary Slavechanske FE (2.15 ha). The analysis of the main types of soil damage and forest ecosystems is carried out. The most common types of forest vegetation conditions, types of forest, species composition and age structure were determined according to the results of the analysis of the forestry and tax rates of damaged plantations. The obtained data indicate that the Pinus sylvestris L. 60-80 year aged, somewhere Quercus robur L., as well as the young Betula pendula Roth and the adjoining plantations of Alnus glutinosa (L.) Gaertn were destroyed as a result of the illegal mining of amber. The forests of nature protection purposes with an area of 84.2 hectares, in particular 71.3 hectares of local reserves and 2.6 hectares of national reserves were damaged on the territory of Zhytomyr RDFH. The estimated area of possible violations in the studied territories is over 3627.90 hectares.The further research prospect is to define features and stimulate ways of the natural renewal of woody vegetation in areas degraded by illegal amber mining, to study the impact of environmental abiotic factors on the process of plant cover renewal, and also to develop own methodology for ecological and economic harm assessment

Population of isomers in decay of the giant dipole resonance

The value of an isomeric ratio (IR) in N=81 isotones ($^{137}$Ba, $^{139}$Ce, $^{141}$Nd and $^{143}$Sm) is studied by means of the ($\gamma, n)$ reaction. This quantity measures a probability to populate the isomeric state in respect to the ground state population. In ($\gamma, n)$ reactions, the giant dipole resonance (GDR) is excited and after its decay by a neutron emission, the nucleus has an excitation energy of a few MeV. The forthcoming $\gamma$ decay by direct or cascade transitions deexcites the nucleus into an isomeric or ground state. It has been observed experimentally that the IR for $^{137}$Ba and $^{139}$Ce equals about 0.13 while in two heavier isotones it is even less than half the size. To explain this effect, the structure of the excited states in the energy region up to 6.5 MeV has been calculated within the Quasiparticle Phonon Model. Many states are found connected to the ground and isomeric states by $E1$, $E2$ and $M1$ transitions. The single-particle component of the wave function is responsible for the large values of the transitions. The calculated value of the isomeric ratio is in very good agreement with the experimental data for all isotones. A slightly different value of maximum energy with which the nuclei rest after neutron decay of the GDR is responsible for the reported effect of the A-dependence of the IR.Comment: 16 pages, 4 Fig

Examination of the astrophysical S-factors of the radiative proton capture on 2H, 6Li, 7Li, 12C and 13C

Astrophysical S-factors of radiative capture reactions on light nuclei have been calculated in a two-cluster potential model, taking into account the separation of orbital states by the use of Young schemes. The local two-body potentials describing the interaction of the clusters were determined by fitting scattering data and properties of bound states. The many-body character of the problem is approximatively accounted for by Pauli forbidden states. An important feature of the approach is the consideration of the dependence of the interaction potential between the clusters on the orbital Young schemes, which determine the permutation symmetry of the nucleon system. Proton capture on 2H, 6Li, 7Li, 12C, and 13C was analyzed in this approach. Experimental data at low energies were described reasonably well when the phase shifts for cluster-cluster scattering, extracted from precise data, were used. This shows that decreasing the experimental error on differential elastic scattering cross sections of light nuclei at astrophysical energies is very important also to allow a more accurate phase shift analysis. A future increase in precision will allow more definite conclusions regarding the reaction mechanisms and astrophysical conditions of thermonuclear reactions.Comment: 40p., 9 fig., 83 ref. arXiv admin note: substantial text overlap with arXiv:1005.1794, arXiv:1112.1760, arXiv:1005.198

Cognitive simulation as integrated innovative technology in teaching of social and humanitarian disciplines

© 2017 Authors. Currently, teachers are searching for innovative educational technologies that enhance the effectiveness of educational activities. The purpose of the paper is the development and approbation of cognitive simulation technology in teaching of social and humanitarian disciplines. Based on the integration of sources of innovation, the authors developed the technology of cognitive simulation aimed at the formation of a structured system of knowledge for social and humanitarian disciplines' subject area. Various forms of cognitive map methods used in the learning process (analysis, synthesis, projection, and simulation) allow developing the analytical and predictive abilities of students, and strengthening their educational motivation. The technology use is proposed for the first time for all socio-humanitarian disciplines in the process of vocational training, which contributes to the formation of inter-subject communications , spatial understanding of events, and transformations of reality. The empirical study carried out by the authors on the implementation of this technology in the educational process (the students of 3 universities, totaling 315 people participated in the study) confirmed the productivity of the technology and the possibility of its adaptation to various disciplines of social and humanitarian sphere