Modeling Carbon Budgets and Acidification in the Mediterranean Sea Ecosystem Under Contemporary and Future Climate

We simulate and analyze the effects of a high CO2 emission scenario on the Mediterranean Sea biogeochemical state at the end of the XXI century, with a focus on carbon cycling, budgets and fluxes, within and between the Mediterranean sub-basins, and on ocean acidification. As a result of the overall warming of surface water and exchanges at the boundaries, the model results project an increment in both the plankton primary production and the system total respiration. However, productivity increases less than respiration, so these changes yield to a decreament in the concentrations of total living carbon, chlorophyll, particulate organic carbon and oxygen in the epipelagic layer, and to an increment in the DIC pool all over the basin. In terms of mass budgets, the large increment in the dissolution of atmospheric CO2 results in an increment of most carbon fluxes, including the horizontal exchanges between eastern and western sub-basins, in a reduction of the organic carbon component, and in an increament of the inorganic one. The eastern sub-basin accumulates more than 85% of the absorbed atmospheric CO2. A clear ocean acidification signal is observed all over the basin, quantitatively similar to those projected in most oceans, and well detectable also down to the mesopelagic and bathypelagic layers.

The influence of carbon component structure of graphene containing shungite on its electrical conductivity.

The investigation of the influence of carbon component structure of graphene containing shungite on its electrical conductivity is carried out. Five shungite samples from three different deposits with the same carbon content equal to 97% were selected as the object of research. It is established that the integral conductivity of specimens which is measured by four-contact method is changed in frames from 600 Sm/m to 2500 Sm/m. For the interpretation of so large scattering of data by equal concentration it was undertaken the investigation of carbon component structure on nano-level which was made by method of high-distinguish raster electron microscopy. By this method on the microscopic section of these specimens was obtained the cards of surface distribution of graphene slides and graphene packets. For the analysis of conductivity of specimens on the basis of these cards it was employed the method of independent channels. This method employs the presentation of specimen as a combination from parallel current-leading channels with following distribution of channel to cubic space blocks. The successive connection of blocks with accounting of slides orientation determines the total resistance of each channel and the parallel connections of all channels determines the specific conductivity of specimen as a whole. For the obtaining the quantity characteristics the whole card was distributed to some more small regions – fields. In this case the obtained results are averaged by the whole square of card. For the analysis of the field the method of square discretization was used. By this method the whole field id distributed to individual squares which dimension is near to the dimension of graphene packet. It was established that the character of structure in each square has two variants: first when the slides of graphene has clear determined spatial orientation ant the second when special orientation is absent and by orientation the squares are neutral. It is made the quantity analysis of neutral squares along the all specimens. It is shown that the normalized quantity of neutral squares is straight proportional to specific conductivity of specimen. The analysis of slides graphene orientation in squares with clear determined spatial orientation is carried out. For investigation of space structure of channel, the square was identified with lateral projection of block along two coordinates. The dependence of block resistance from the slide orientation is found. It is shown that the block resistance by the flowing of current across the graphene slides is more than order exceeds the resistance by the flowing of current along the slides of graphene. It is shown that the most role in formation of channel resistance play the blocks which graphene slides are oriented across the current flowing. By the adding of channels along the structure of volume unit it was founded the specific conductivity of specimen as a whole. It is established that the obtained meanings of conductivity for all specimens exceed the obtained by contact method on several times. As a reason of this exceeding it is established the absence of accounting the influence of enough small conductivity of intervals between slides and packets and also the absence of accounting of incomplete filling of squares by periodic structures. It is shown that the optimal in plane of correspondence to experiment is the introduce the normalization coefficient of conductivity of intervals which is equal to 0,2222. For the accounting of incomplete filling of squares by periodic structures it was carried out the binary discretization of most typical blocks with the resolution near 0,2 nm which is near the thickness of graphene slide. Along the obtained selection there was the averaged coefficients of filling of carbon which are equal from 0,10 to 0,15 parts for the whole volume of blocks. With the normalized conductivity of intervals and coefficients of filling of blocks it was found the integral conductivity for all specimens. It is shown that the obtained values are near the measured by contact method in the precision not more than 37%. In brief it is discussed the quality reason of apparent paradoxical increasing of integral conductivity by decreasing on structural character of carbon. It is established that the main reason of this increasing is the decreasing of contribution of graphene slides having large resistance which are oriented across the flowing of current.

Investigation of electrical conductivity of graphene-contained shungite using the high-resolution scanning electron microscopy.

The electrical conductivity of carbon component of graphene-contained shungite is investigated. The basis of this investigation is the statistic processing of carbon distribution cards which are obtained by high-resolution scanning electron microscopy. For the original card of carbon distribution it is proposed the method of building of contour card with following conversion its into binary card which consist of net from cells having black and white colours. The statistic analysis of repeating of binary card structure in the frame of selected region having square form. It is shown that the relative concentration of cells both colour in selected region by the increasing of its dimensions undertakes the scattering which increases when dimension of region is decreased. It is found the minimal dimension of region in which the deflection of relative concentration of cells of unit colour from the constant value of this concentration is not more then 20%. This dimension is received as flat-characteristic of middle-statistic block which relative properties repeats the relative properties of structure as a whole. From the conditions of isotropy of carbon component of shungite the space model of symmetrical along three axis cubic middle-statistic block which consist of cubic cells both colours. It is established that black cells correspond to large conductivity and white cells correspond to small conductivity. In connection with the direction of electric current which flows along the flat of card it is proposed two kinds of graphene packets orientation. In this case the black cells having large conductivity are identified with graphene packets where the current flows along the graphene slides and the white cells having small conductivity are identified with graphene packets where the current flows across the graphene slides. For the analysis of conductivity of middle-statistic block the model of current tubes is proposed. From the whole structure of block the two kinds of tubes are selected. This kinds of tubes correspond to different cases of alternate with each other black and white cells. The structure of these tubes is identified with the set of favourable and non-favourable oriented graphene packets. On the basis of known resistances of graphene slide it is calculated the resistances of packets having favourable and non-favourable orientations. Using this resistances of packets the resistances of tubes are calculated. It is shown that the main role in resistance of tubes formation plays the resistance of intervals between graphene slides and graphene packets. Using obtained resistances of tubes it is found the resistance of middle-statistic block which has the parallel connections of tubes. On the basis of middle-statistic block resistance it is found the specific resistance and the back proportional to this resistance the specific conductivity of carbon component of shungite. It is shown that the main parameter which determines the resistance and conductivity is the specific resistance of interval between graphene slides and graphene packets. It is execute the comparison of determined specific conductivity with the observed in experiments specific conductivities of shungite received from different natural deposits. The some practical remarks and some little defects are proposed. The possibilities of improvement of proposed model are discussed.

Evaluation of the Stability of Carbon Conductor in the Cathode of Aqueous Rechargeable Lithium Batteries against Overcharging

Three major components in a cathode of aqueous rechargeable lithium batteries are the active material, the polymer binder, and the carbon conductive additive. The stability of each component in the battery is the key to long service life. To evaluate the stability of the carbon component, we introduce here a quick and direct testing method. LiMn2O4 is chosen as a typical active material for the preparation of the cathode, with polyvinylidene fluoride (PVdF), and a commercial carbon, which is chosen among Acetylene black, superP, superP-Li, Ketjen black 1, Ketjen black 2, Graphite, KS-6, splintered glassy carbon, and splintered spherical carbon. This method reveals the correlation between the electrochemical stability of a carbon and its physical and structural properties. This helps researchers choose the right carbon component for a Li-ion cathode if they want the battery to be robust, especially at near full state of charge.

Expansion / shrinkage of bottom masses hearth during firing

The actualization of the problem of shrinkage phenomena in the process of firing the bottom, contributing to the opening of joints and the formation of cracks, is shown. The modern methods and means of studying expansion / shrinkage of the bottom masses during firing are analyzed. The expansion / shrinkage of bottom masses, differing in the ratio of the carbon component (anthracite) and artificial graphite in their composition, was investigated. It has been established that shrinkage phenomena decrease in a row from anthracite mass to graphitoanthracite. Studies have shown that the difference in the scale of linear changes during structural shrinkage is quite significant ― about 20 %. It was noted that the minimization of shrinkage phenomena contributing to the opening of joints and the formation of cracks is one of the factors to reduce the risk of leakage of the bottom of the cell. In this regard, it is advisable to optimize the rate of shrinkage of the bottom masses during the firing process at the stage of its structural adjustment, taking into account the conditions of their operation

The research of the effect of oxidizing agents on the burning process of the carbon-containing component of ceramic masses and their firing properties

The efficiency of using different oxidizing agents to intensify the burnout of the organic component of ceramic masses is investigated. The ceramic masses contained coal flotation wastes with a high carbon content as a fuel-mineral additive. Various inorganic salts, which are oxygen donors during the firing of ceramic masses and form oxidizing agents O2, NO2, N2O during their thermal decomposition, are considered. A new calculation method for determining the content of an oxidizing salt in a ceramic mixture is proposed. This method takes as a basis the amount of «effective oxygen» that released during the thermal decomposition of the oxidizing agent, but not its mass, as it was before. The method allows calculating the rational content of an oxidizing agent necessary for efficient combustion of the carbon component of fuel-mineral additives. When calculating, it is necessary to take into the composition of the organic part of the additive, its content in the ceramic mass and the degree of carbon oxidation. Calculation of the rational content of the oxidizing agent according to this method allows avoiding its excessive and economically unreasonable use. The effect of oxidizing agents and their combinations on the burnout of the carbon component and the firing properties of the masses for wall ceramics is studied. The masses contained 15 % of coal flotation waste with a carbon content of 29 %. It was found that the use of oxidizing agents accelerates the burnout of the organic part of the masses, improves the appearance and mechanical properties of ceramic samples. The use of combined oxidizing agents with different decomposition temperatures makes it possible to create an oxidizing medium in a wider temperature range. This positively effects on the mechanical properties of ceramics. The optimal combinations of oxidizing agents NH4NO3+Ca(NO3)2 і NH4NO3+NaNO3, which made it possible to obtain ceramic samples with a compressive strength 10 МПа, were determined. This mechanical strength meets the requirements of the State Standard of Ukraine B M.2.7-61: 2008 in part of ordinary brick of the M100 brand.