The stress transmission universality classes of periodic granular arrays

The transmission of stress is analysed for static periodic arrays of rigid grains, with perfect and zero friction. For minimal coordination number (which is sensitive to friction, sphericity and dimensionality), the stress distribution is soluble without reference to the corresponding displacement fields. In non-degenerate cases, the constitutive equations are found to be simple linear in the stress components. The corresponding coefficients depend crucially upon geometrical disorder of the grain contacts

Interconnectivity of habitats in soil:combining X-ray micro tomography and thin sectioning to reveal fungal-soil structure interactions

The extreme heterogeneity and interconnectivity of the 3-dimensional pore space within soil makes it a unique habitat for the diverse microbial population and has a pivotal role in microbial interactions. Manipulation and quantification of the 3-dimensional pore space and the spatial distribution of micro-organisms is therefore essential if we are to fully understand microbial interactions. Here we pack soil microcosms at different bulk-densities to manipulate soil structure and use x-ray micro tomography and soil thin sections to analyse the effect on the connectivity of the pore volume and on fungal exploration

The missing stress-geometry equation in granular media

The simplest solvable problem of stress transmission through a static granular material is when the grains are perfectly rigid and have an average coordination number of $\bar{z}=d+1$. Under these conditions there exists an analysis of stress which is independent of the analysis of strain and the $d$ equations of force balance $\nabla_{j} \sigma_{ij}({\vec r}) = g_{i}({\vec r})$ have to be supported by $\frac{d(d-1)}{2}$ equations. These equations are of purely geometric origin. A method of deriving them has been proposed in an earlier paper. In this paper alternative derivations are discussed and the problem of the "missing equations" is posed as a geometrical puzzle which has yet to find a systematic solution as against sensible but fundamentally arbitrary approaches.Comment: 10 pages, 4 figures, accepted by Physica

Overlapping Resonances Interference-induced Transparency: The S0→S2/S1S_0 \to S_2/S_1 Photoexcitation Spectrum of Pyrazine

The phenomenon of "overlapping resonances interference-induced transparency" (ORIT) is introduced and studied in detail for the $S_0 \to S_2/S_1$ photoexcitation of cold pyrazine (C$_4$H$_4$N$_2$). In ORIT a molecule becomes transparent at specific wavelengths due to interferences between envelopes of spectral lines displaying overlapping resonances. An example is the $S_2\leftrightarrow S_1$ internal conversion in pyrazine where destructive interference between overlapping resonances causes the $S_0 \to S_2/S_1$ light absorption to disappear at certain wavelengths. ORIT may be of practical importance in multi-component mixtures where it would allow for the selective excitation of some molecules in preference to others. Interference induced cross section enhancement is also shown.Comment: 13 pages, 7 figure

Mineralogy and prospect of noble metals of gold-bearing ore breccias from ore fields of polymetallic deposits of Ore Altai

The object of the present study are the ore-bearing breccias of the worked-out lower-middle Devonian gold-silver barite-polymetallic Zmeinogorsky deposit belonging to the cognominal ore district and the conserved massive sulfide Chekmar deposit belonging to the Leninogorsk ore district. Both ore districts occupy an adjacent position within the northeastern depression zone of the Ore Altai megatrough. A brief structural and geological description of near-fault ore-bearing breccias, which developed within the peripheral parts of the deposits, is given. Analysis of petrographic composition of breccia fragments and their cementing material allowed to define barite-quartzite breccias of the Zmeinogorsky deposit and pyritized adularia-quartz metasomatites formed upon acidic igneous rocks and greenschists of the Chekmar deposit. Results of mineralogical studies with use of raster electron microscope show that there are ore minerals microinclusions in the detrital material and cement of breccias. Barite-quartzite breccias of Zmeinogorsk deposit contain barite, galena, Hg and Sb containing polymineral formations, tetrahedrite-boulangerite, bromargyrite, leucoxene. Microquartzites of these breccias mostly consist of quartz. Chekmar deposit ore breccias detrital material contains pyrite, barite, arsenopyrite, galena, sphalerite, zircon, titanite, leucoxene and REE minerals. Quartzitic compound of these breccias is cryptocrystalline and consists of quartz and adularia with admixtures of sericite and pyrite. Due to results obtained by use of SEM it was stated that barite, sulfides and sulfosalts of breccias contain noticeable amounts of dissipated Au, Pd, Pt, Ir. ICP-MS results confirm that studied ore breccias contain such noble metals as Au, Ag, Pd, Pt. Moreover, noble metals contents in Zmeinogorsk deposit breccias reach industrial standards while noble metals of Chekmar deposit ores can be extracted along with the processing of basic massive sulfide ores. Further study of ore breccias is important as these breccias can be considered as a noble metals containing subformation among polymetallic ores of Ore Altai

CONDITIONS OF DEVELOPMENT OF PROFESSIONAL MOTIVATION OF STUDENTS

Basing on the analysis of the structure of the motivational sphere of the personality, the identification of the essence of professional motivation in the student community, the article theoretically and experimentally substantiates the effectiveness of the complex of psychological and pedagogical conditions for the development of professional motivation of students in higher education: monitoring of personal and professional growth in the process of professional training; development and implementation of a system of methods and forms aimed at forming a professionally oriented process of cognition: psychological consultations on issues of professional orientation, personal self-determination, training on the development of professionally important qualities and motives of professional activity; modeling situations of upcoming professional activities; creation of the educational environment of the university for the application of acquired professional knowledge and skills. The article describes an empirical study of the structure of the motivational complex and the level of professional motivation of students. According to the results of the experiment, the need to create special educational conditions that underlie the development and implementation of the elective program aimed at increasing the level of professional motivation of students in higher education is revealed

Material composition of the basalt-trachyte series of the early Devonian of the Saralin graben-rift

The article clarifies the structural-tectonic position of the Saralin graben. It is determined that, along with the Balyksinsky graben located to the south and the Goryachegorsky volcanic plateau to the north, they are the connecting structural links between the Kuznetsk-Alatau alkaline province and the adjacent Minusinsk trough. In the early Devonian, the alkaline province was formed as a vaulted-block structure (the "shoulder" of the rift), and the Minusinsk deflection as a depression with the dominant volcanism in it. The boundary between these positive and negative structures was the deep Balyksinsko-Saralinsky fault

Comparative Study of Hydrogen Adsorption in Slit-like Pores of Carbon Adsorbents and on Fullerene Molecules

Adsorption of hydrogen in slit-like pores of carbon adsorbents and on fullerene molecules was investigated using the classical density functional theory. Hydrogen adsorption in a gap between two graphene walls was calculated at different temperatures and pressures. The obtained results agree with the data found using the Dubinin theory of the volume pore filling and with the available molecular dynamics results. It has been shown that conventional carbon adsorbents corresponding to the slit-like model and fullerene materials should have approximately equal storage capacities. However, such a capacity is sufficient for practical storage and use of hydrogen at low temperatures only (at about 20 K), and at room temperatures some special active sites of adsorption should be used to solve the problem under consideration. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3517