Взрывоопасность угольной пыли и метана в горном деле

Данная статья посвящена проблеме предотвращения аварий на предприятиях горнодобывающей промышленности за счёт влияния. Рассматриваются причины повышения содержания газа в горных выработках. Дана сравнительная характеристика угольной пыли и метана по их опасности. Выявлено, что угольная пыль опаснее метана. Приведены меры по профилактике аварийности на горнодобывающих предприятиях. This article is devoted to the prevention of accidents in the mining industry at the expense of influence. It discusses reasons for the increase in gas content in mine workings. The author describes comparative characteristics of coal dust and methane at their danger. It is revealed that the coal dust is more dangerous than methane. The author gives measures for the prevention of accidents at mining enterprises

Developing a Framework for Automated Scenario- Based e-Learning Design

Scenario-based e-learning can be used to enable students to develop expertise, in situations that are rare or infrequent, too hazardous for the inexperienced, too expensive to permit practice and failure, or simply not available. Developing automated courses requires significant technical ability, separate from the subject expertise of the educator. This paper introduces a framework developed to simplify this process, along with a scenario authoring and cloud-based training environment, Pandora

Tighter bounding volumes for better occlusion culling performance

Bounding volumes are used in computer graphics to approximate the actual geometric shape of an object in a scene. The main intention is to reduce the costs associated with visibility or interference tests. The bounding volumes most commonly used have been axis-aligned bounding boxes and bounding spheres. In this paper, we propose the use of discrete orientation polytopes (\kdops) as bounding volumes for the specific use of visibility culling. Occlusion tests are computed more accurately using \kdops, but most importantly, they are also computed more efficiently. We illustrate this point through a series of experiments using a wide range of data models under varying viewing conditions. Although no bounding volume works the best in every situation, {\kdops} are often the best, and also work very well in those cases where they are not the best, therefore they provide good results without having to analyze applications and different bounding volumes

Limb bone scaling in hopping diprotodonts and quadrupedal artiodactyls

Bone adaptation is modulated by the timing, direction, rate, and magnitude of mechanical loads. To investigate whether frequent slow, or infrequent fast, gaits could dominate bone adaptation to load, we compared scaling of the limb bones from two mammalian herbivore clades that use radically different high-speed gaits, bipedal hopping and quadrupedal galloping. Forelimb and hindlimb bones were collected from 20 artiodactyl and 15 diprotodont species (body mass M 1.05 - 1536 kg) and scanned in clinical computed tomography or X-ray microtomography. Second moment of area (Imax) and bone length (l) were measured. Scaling relations (y = axb) were calculated for l vs M for each bone and for Imax vs M and Imax vs l for every 5% of length. Imax vs M scaling relationships were broadly similar between clades despite the diprotodont forelimb being nearly unloaded, and the hindlimb highly loaded, during bipedal hopping. Imax vs l and l vs M scaling were related to locomotor and behavioural specialisations. Low-intensity loads may be sufficient to maintain bone mass across a wide range of species. Occasional high-intensity gaits might not break through the load sensitivity saturation engendered by frequent low-intensity gaits

Applications of enantioselective halolactonization reactions, synthesis of photocaged compounds for identifying neurons based on function, and progress towards the total synthesis of alstoscholarisine E

Recently the Martin group developed a bifunctional organic catalyst that promotes highly efficient enantioselective halolactonization reactions for olefinic acids. Using the BINOL-amidine catalyst we invented, our group was able to perform halolactonization reactions on a broad array of substrates. Herein we describe the synthetic utility of this method through a concise synthesis of (+)-disparlure, along with the preparation of F ring synthons for the natural product kibdelone C. As part of a separate project, in collaboration with the Zemelman research group, we are working to design a system for identifying behaviorally relevant assemblies of neurons in awake animals. This novel technique identifies active neurons and tags them using fluorescent proteins that are expressed upon irradiation of the neuron with visible light. This system hinges on the preparation on light sensitive derivatives of a variety of repressor protein ligands using “cages” or “photocages.” Toward this end, we prepared photocaged derivatives of anhydrotetracycline and vanillic acid. Finally, we disclose our progress towards the total synthesis of alstoscholarisine E, a natural product isolated in 2014 that was found to be a strong promoter of adult neuronal stem cell proliferation. We envisioned a convergent synthesis where skatole and a hetero-Diels-Alder product could be joined through a metal catalyzed coupling to form the tetracyclic core of the molecule, which could then be easily transformed to alstoscholarisine E through an olefin reduction followed by a reductive cyclization. Accessing our desired hetero-Diels-Alder product quickly was paramount to the effectiveness of this route, and thus, we developed a method to access hetero-Diels-Alder precursors in one step starting from readily available hexahydrotriazines.Chemistr