Journal articles on the topic 'Volumetric block proportion'
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Zhu, Guojin, Yu Ding, and Yajun Cao. "The Effect of Block-Matrix Interface of SRM with High Volumetric Block Proportion on Its Uniaxial Compressive Strength." Applied Sciences 13, no. 6 (March 8, 2023): 3463. http://dx.doi.org/10.3390/app13063463.
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The soil–rock mixture (SRM), as a heterogeneous and discrete geomaterial, can be widely found in nature and may present difficult design and construction issues for structures within or on top of them. Engineers face a difficult problem when determining the mechanical behavior of geomaterials with SRM, especially those with a high volumetric block proportion (VBP). As it is often very difficult to prepare undisturbed and representative samples of these materials. Thus, this paper proposes a novel method that can generate SRM models with a high VBP and produce a block-matrix interface (BMI) around the rock block, which can simulate unwelded SRM in nature. Then, the finite difference method (FDM) is applied to simulate uniaxial compression tests. The conformity of the numerical simulation results with the experimental results shows that the method is reasonable and effective. In addition, the effect of the strength of the BMI, the thickness of the BMI, and the geometrical shape of the rock blocks on the uniaxial compressive strength (UCS) of the SRM are also investigated. The modelling approach proposed in this paper is able to generate BMI in SRMs and enables the effect of the BMI on the SRMs’ properties to be better investigated in numerical simulations. This method can overcome the difficulties of preparing representative and undisturbed experimental cores while saving cost and improving efficiency. Simultaneously, the method proposed in this paper is promising to be extended to three dimensions.
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Wang, Shengnian, Yue Li, Xinqun Gao, Qinpei Xue, Peng Zhang, and Zhijian Wu. "Influence of volumetric block proportion on mechanical properties of virtual soil-rock mixtures." Engineering Geology 278 (December 2020): 105850. http://dx.doi.org/10.1016/j.enggeo.2020.105850.
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Nikolaidis, G., and C. Saroglou. "ENGINEERING GEOLOGICAL CHARACTERISATION OF BLOCK-IN-MATRIX ROCKS." Bulletin of the Geological Society of Greece 50, no. 2 (July 27, 2017): 874. http://dx.doi.org/10.12681/bgsg.11793.
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Block-in-matrix rocks (“bimrocks”) are complex, mixed and heterogeneous formations of competent blocks embedded in weaker matrix. The inherent difficulty of sampling and consequently, laboratory testing of bimrocks leads to considerable challenging in geotechnical design and assessment of their engineering behaviour. An approach for the characterisation of “bimrocks” is the use of stereological analysis that extrapolates one-dimensional or two dimensional data to estimate the block volumetric proportion. This has been an established approach of dealing with bimrocks and melanges for the last two decades. This paper presents the parameters that are considered important for the engineering characterisation of such complex formations, while a case study from a bimrock in NW Greece is discussed.
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Ramos-Cañón, Alfonso Mariano, Lady Carolina Castro-Malaver, Nelly Vanessa Padilla-Bello, and Carlos Alberto Vega-Posada. "Incertidumbre en la determinación del Porcentaje Volumétrico de Bloques de BIMrocks/BIMsoil a partir de información unidimensional." Revista Boletín de Geología 42, no. 1 (January 1, 2020): 69–80. http://dx.doi.org/10.18273/revbol.v42n1-2020004.
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La caracterización mecánica de depósitos de materiales heterogéneos (BIMrocks/BIMsoil – Block in Matrix) requiere del conocimiento de la cantidad de bloques inmersos en una matriz débil (Proporción Volumétrica de Bloques, PVB). La aleatoriedad en el proceso de formación de dichos depósitos impide obtener información unívoca mediante estudios geotécnicos convencionales. Es posible reconocer que a medida que aumenta el número y la profundidad de las perforaciones, se disminuye la incertidumbre en la determinación de la PVB, sin embargo, la cuantificación de la disminución de la incertidumbre no ha sido abarcada de manera comprensiva. La determinación de la PVB en materiales BIMrock/BIMsoil tiene asociada una incertidumbre que se ha estudiado con modelos físicos y analíticos. Dichos modelos no consideran la influencia de factores como el tamaño, forma y orientación de los bloques, que simultáneamente inciden en la cuantificación de la incertidumbre en la PVB.En este trabajo se desarrolló un algoritmo y se implementó computacionalmente para analizar la influencia de la longitud y el número de las perforaciones, junto con la forma y orientación de los bloques, sobre el nivel de incertidumbre en la determinación de la PVB. Los resultados sugieren que a mayor investigación del subsuelo (número y longitud de perforaciones), independiente de la forma, tamaño y orientación de los bloques, se disminuye la incertidumbre epistémica en la PVB. Sin embargo, dicha incertidumbre tiene un límite inferior que obedece a la naturaleza aleatoria propia de la formación del material BIMrock/BIMsoil
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Samsonova, Maria, Elvira Semenova, Christina Kotova, and Leonid Salogub. "Additional heat loss of jamb in enclosing structures." E3S Web of Conferences 263 (2021): 03017. http://dx.doi.org/10.1051/e3sconf/202126303017.
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One of the urgent problems today is to increase the energy efficiency of civil buildings. There is a need at the design stage to choose structures and design solutions that will compensate for the increasing consumption of energy resources in civil engineering. This article compares different building envelopes used in the construction of residential buildings: a volumetric block and a wall made of aerated concrete blocks. To determine the most energy efficient design solution construction is compared in different climatic regions. One of the most vulnerable places of a wall, from the point of view of energy efficiency, is a window jamb. In this article, an analysis is carried out to determine the construction with the lowest heat loss window jambs. Using the ELCUT software temperature fields and additional heat flux densities are calculated. According to the calculation, the proportion of heat loss due to window slope from heat loss according to the surface of the structure was determined. The heat flux density of the homogeneous section of the wall of the volume block is 1.28 times higher on average than in the aerated concrete wall. Regardless of the climatic conditions, the junction of the window jamb in buildings made of insulated panels of volumetric blocks is more energy efficient than the same junction in a building with aerated concrete walls.
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Kahraman, S., M. Alber, M. Fener, and O. Gunaydin. "An assessment on the indirect determination of the volumetric block proportion of Misis fault breccia (Adana, Turkey)." Bulletin of Engineering Geology and the Environment 74, no. 3 (September 11, 2014): 899–907. http://dx.doi.org/10.1007/s10064-014-0666-9.
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Wang, Shuaifeng, Yinlian Yi, Xiaochang Li, Shaoqiang Zhang, and Zixin Zhang. "Investigation of Volumetric Block Proportion (VBP) Effect on Excavation-Induced Ground Response of Talus-like Rock Mass Based on DEM Simulations." Materials 15, no. 24 (December 14, 2022): 8943. http://dx.doi.org/10.3390/ma15248943.
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Due to the complexity of the talus-like rock mass with different values of volumetric block proportion (VPB), it is thus crucial to explore the VBP effect on the excavation-induced ground responses. We conduct a series of 2D DEM (discrete element method) simulations on a common circular tunnel excavation in the talus-like rock mass with different VBPs (0%, 15%, 50%, 85% and 100%). For each VBP, two support scenarios, i.e., unsupported and supported by a rigid lining, are considered. The micro characteristics of the excavation-induced ground responses, including the contact force, force chain, coordination number and shear-slip contact, and the stress distribution and ground settlement are elaborated in detail. Accordingly, three types of talus-like rock masses are identified as soil-, hybrid- and rock-types, corresponding to VBP = 0–15%, 50%, and 85–100%, respectively. It is found that the lining support is essential for maintaining the ground stability of a tunnel excavation in the soil- and hybrid-type talus-like rock masses while the backbones formed by rock blocks in the rock-type talus-like rock mass can provide a certain support for the surrounding ground. Our findings have important implications for optimizing the construction scheme of tunnel excavation in different types of talus-like rock masses.
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Winarno, S. "Preliminary Study on Hand-cast Lightweight Concrete Block using Raw Rice Husk as Aggregate." IOP Conference Series: Earth and Environmental Science 933, no. 1 (November 1, 2021): 012005. http://dx.doi.org/10.1088/1755-1315/933/1/012005.
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Abstract Raw rice husk is an abundantly available waste material in Indonesia as one of rice producing countries. Due to rice husk is light in weight and convex in shape, this paper presents a preliminary application of raw rice husk as natural aggregate in order to make lightweight concrete blocks. Concrete specimens contained Portland Cement, filler, and raw rice husk, in which the mix proportion was in volumetric ratio, i.e 1.25 cement and 2.75 filler constantly, whereas dosage of rice husk varied from 8.5 to 10. The production of the concrete block was by mixing the ingredients together and then the mixture was casted and compacted on moulds by hand manually. Series laboratory experiments were accomplished to analyse the compressive strength and density. For this, four groups of mixes were prepared. The results have shown that the higher proportion of rice husk is the lower its compressive strength and the lighter its density. At proportion of 1,25 cement: 2,75 fillers: 8,5 raw rice husks, the compressive strength is 26.64 kg/cm2 and this satisfies the minimum standard (25 kg/cm2). Unfortunately, the density is 1,536.73 kg/m3 and it is higher than the maximum standard of 1,400 kg/m3. Thus, it is important to research further by making and testing some improved specimens with more cement, more rice husk, and less filler to fulfil strength and density.
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Tuo, Wang, Qi Fuzhou, and Chang Jucai. "Analysis of Energy Transmission and Deformation Characteristics of Coal-Rock Combined Bodies." Geofluids 2022 (June 28, 2022): 1–11. http://dx.doi.org/10.1155/2022/5304250.
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A coal-rock system is a common combination form in coal mines. In order to explore the energy interchange law of a coal-rock combined body and the interaction relationship between the two bodies, loading tests of coal-rock combined bodies with different height ratios were carried out. The loading path of rock in coal-rock combined bodies was demonstrated by means of a single loading and unloading test of the same-sized rock sample. Furthermore, a method to calculate rock energy was proposed based on the area of the loading and unloading curve. The experimental results show that the greater the surrounding rock pressure is, the smaller increase rate of lateral and volumetric strain in the postpeak stage will be when the same height ratio is present. An increase in the surrounding rock pressure causes an increase in the total strain energy density of small-sized rock samples. However, the total strain energy density is always greater than the elastic strain energy density. And the elastic and dissipated strain energy densities also increase, along with the energy dissipation with unloading. When the proportion of coal bodies increases, the energy accumulation also shows an increasing trend. When the height of the coal is greater than half the height of the complete specimen, the coal energy proportion is greater than 60%. After reaching the yield load, the energy in the coal body is dissipated in forms such as plastic deformation, internal damage, block friction, radiation energy, and kinetic energy. Therefore, the energy released is, in part, reflected in the rock body.
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Douglas, D. Stokke, and G. Manwiller Floyd. "Proportions of Wood Elements in Stem, Branch, and Root Wood of Black Oak (Quercus Velutina)." IAWA Journal 15, no. 3 (1994): 301–10. http://dx.doi.org/10.1163/22941932-90000612.
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The volumetrie proportions of vessel elements, fibres, rays, and axial parenchyma plus vasicentric tracheids were determined for the stern, branch and root wood of threc black oak (Quercus velutina Lam.) trees. There were statistical differences in the proportions of wood elements between locations within the trees sampled, i.e., branches, sterns, roots, oblique roots, and lateral roots. Branches had the highest proportion of vesseI elements, whereas sterns had the greatest proportion ofaxial parenchyma plus vasicentric tracheids. The highest proportions of rays were found in root wood. Fibre proportion was greatest in the stern and branch wood.
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Likhanov, Vitaly A., and Oleg P. Lopatin. "Usage of Rapeseed Oil and Ethanol in a Diesel Engine." Engineering Technologies and Systems 32, no. 3 (September 30, 2022): 373–89. http://dx.doi.org/10.15507/2658-4123.032.202203.373-389.
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Introduction. Alternative fuels in IC-engines make it possible to reduce the harmful effects of exhaust gases on the environment without the use of expensive cleaning systems, diversify the fuel market, and reduce the consumption of non-renewable energy recourses, while research aimed at studying the use of alternative fuels makes it possible to find optimal options for replacing non-renewable raw materials. The purpose of the work is to study the effect of using ethanol in a standard tractor diesel engine with volumetric mixing and combustion from flare resulting from the autoignition of a rapeseed oil pilot portion and to optimize separate cyclic fuel deliveries to obtain maximum energy and environmental effect. Materials and Methods. The article deals with the description of the results of the use of rapeseed oil and ethanol in a serial tractor diesel engine of dimension 2F 10.5/12.0 with separate fuel injection directly into the combustion chamber. In the course of experimental studies, the working process was indicated by a piezo quartz pressure sensor installed in the cylinder head, fuel and air consumption were measured, and samples of exhaust gases to study the gas composition and determine the content of toxic components and smokiness were taken. Results. The exact ethanol and rapeseed oil delivery was determined; the values of the average effective pressure, the average temperature of gases in the cylinder, and active and full heat generation were obtained. It is shown that with an increase in the cyclic ethanol delivery, the proportion of heat from kinetic combustion increases, while the diesel process is characterized by an increase in the proportion of diffusion combustion when the load increases. The analysis of the processes inside the cylinder when the engine runs on ethanol and rapeseed oil in comparison with the traditional diesel process is carried out. Discussion and Conclusion. The use of rapeseed oil and ethanol can completely replace the traditional fuel of petroleum origin for an operating diesel engine by installing additional fuel equipment and modifying the head of cylinder block through mounting an additional nozzle. In this case, the environmental performance of the diesel engine improves significantly.
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Napoli, Maria Lia, Lorenzo Milan, Monica Barbero, and Edmund Medley. "Investigation of Virtual Bimrocks to Estimate 3D Volumetric Block Proportions from 1D Boring Measurements." Geosciences 12, no. 11 (November 4, 2022): 405. http://dx.doi.org/10.3390/geosciences12110405.
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Serious deficiencies in ground characterization, analysis and design at engineering works can occur when working with bimrocks (block-in-matrix rocks) and bimsoils (block-in-matrix soils). Since the 1990s, serious technical problems at engineering works performed in bimrocks/bimsoils spurred practical research, which revealed that the behavior of these geomaterials is directly related to the volumetric block proportions (VBPs). However, the way that VBPs can be confidently and correctly estimated remains an ongoing critical issue that still frustrates designers, contractors and owners. Stereological techniques can be applied to overcome this challenge by inferring 3D block contents from in situ 1D and 2D measurements, but the estimates have often been demonstrated to be erroneous. This paper presents findings from a computer-aided reinvestigation, revalidation and extension of Medley’s work of 1997 and subsequent researchers to provide approachable yet statistically robust methods to limit the uncertainty associated with estimates of 3D VBPs generated from 1D boring/scanline measurements. To this aim, a specialized Matlab code was created and virtual drilling programs were performed through 3D computer-generated bimrock models. Supported by extensive statistical-based investigations, a design chart is provided that updates and extends Medley’s 1999 chart relating uncertainty in estimates of VBP as a function of total boring/scanline lengths.
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Tsiambaos, G. "ENGINEERING GEOLOGICAL BEHAVIOUR OF HETEROGENEOUS AND CHAOTIC ROCK MASSES." Bulletin of the Geological Society of Greece 43, no. 1 (January 19, 2017): 183. http://dx.doi.org/10.12681/bgsg.11173.
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The engineering characterization of heterogeneous and complex geological formations for estimating their rock mass strength and deformability characteristics constitutes a challenge to geo-scientists and engineers dealing with the design and construction of slopes and tunnels. Mélanges and similar heterogeneous mixtures of hard blocks in weaker matrix, known as “bimrocks”, present an overall strength significantly greater than the matrix strength, because the presence of rock blocks, above a threshold volumetric proportion, influences the mechanical characteristics and the behaviour of these rock masses. Moreover, recent studies have shown that the strength and mechanical behaviour of heterogeneous and composite rock masses such as flysch and molasses consisting of alternating layers of competent and incompetent rocks are governed by the presence and volumetric percentage of the interlayers of the weaker rocks.
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O'Sullivan, M. J., G. S. Bodvarsson, K. Pruess, and M. R. Blakeley. "Fluid and Heat Flow In Gas-Rich Geothermal Reservoirs." Society of Petroleum Engineers Journal 25, no. 02 (April 1, 1985): 215–26. http://dx.doi.org/10.2118/12102-pa.
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Abstract Numerical simulation techniques are used to study the effects of noncondensable gases (CO2) on geothermal reservoir behavior in the natural state and during exploitation. It is shown that the presence Of CO2 has a large effect on the thermodynamic conditions of a reservoir in the natural state, especially on temperature distributions and phase compositions. The gas will expand two-phase zones phase compositions. The gas will expand two-phase zones and increase gas saturations to enable flow of CO2 through the system. During exploitation, the early pressure drop primarily results from "degassing" of the system. This primarily results from "degassing" of the system. This process can cause a very rapid initial pressure drop, on process can cause a very rapid initial pressure drop, on the order of megapascals, depending on the initial partial pressure of CO2. The flowing gas content from wells can pressure of CO2. The flowing gas content from wells can provide information on in-place gas saturations and provide information on in-place gas saturations and relative permeability curves that apply at a given geothermal resource. Site-specific studies are made for the gas-rich, two-phase reservoir at the Ohaaki geothermal field in New Zealand. A simple lumped-parameter model and a vertical column model are applied to the field data. The results obtained agree well with the natural thermodynamic state of the Ohaaki field (pressure and temperature profiles) and a partial pressure of 1.5 to 2.5 MPa [217 to 363 psi] is calculated in the primary reservoirs. The models also agree reasonably well with field data obtained during exploitation of the field. The treatment of thermophysical properties of H2O/CO2 mixtures for different phase compositions is summarized. Introduction Many geothermal reservoirs contain large amounts of non-condensable gases, particularly CO2. The proportion of noncondensable gas in the produced fluid is an extremely important factor in the design of separators, turbines, heat exchangers, and other surface equipment. In the reservoir itself, the presence of CO2 significantly alters the distribution of temperature and gas saturation (volumetric fraction of gas phase) associated with given heat and mass flows. Therefore, when modeling gas-rich reservoirs it is essential to keep track of the amount of CO2 in each gridblock in addition to the customary fluid and heat content. Several investigators have considered the effects of CO2 on the reservoir dynamics of geothermal systems. A lumped-parameter model using one block for the gas zone and one for the liquid zone was developed by Atkinson et al. for the Bagnore (Italy) reservoir. Preliminary work on the Ohaaki reservoir was carried out by Zyvoloski and O'Sullivan, but these studies were limited because-the thermodynamic package used could only handle two-phase conditions. Generic studies of reservoir depletion and well-test analysis also were made in the previous works. The present study describes the effects of CO2 in geothermal reservoirs in a more complete and detailed way. We emphasize the potential for using the CO2 content in the fluid produced during a well test as a reservoir diagnostic aid, and as a means of gaining information about relative permeability curves. The aim of the present study is to investigate the effects of CO2 on both the natural state of a reservoir and its behavior under exploitation. Several generic simulation studies are described. First, the effect of CO2 on the depletion of a single-block, lumped-parameter reservoir model is briefly examined. Secondly, the relationship between the mass fraction Of CO2 in the produced fluid and the mass fraction in place in the reservoir is studied. It is demonstrated that in some cases the in-place gas saturation can be determined for a given set of relative permeability curves. Finally, the effects of CO2 on the permeability curves. Finally, the effects of CO2 on the vertical distribution of gas saturation, temperature, and pressure of geothermal reservoirs in the natural state are pressure of geothermal reservoirs in the natural state are investigated. The numerical simulator with the H2O/CO2 thermodynamic package is applied to field data from the Ohaaki (formerly Broadlands) geothermal field in New Zealand. Two simple models of the 1966–74 large-scale field exploitation test of the Ohaaki reservoir are presented. The first is a single-block, lumped-parameter model similar to those reported earlier by Zyvoloski and O'Sullivan and Grant. In the former work, a less accurate thermodynamic package for H2O/CO2 mixtures is used; the latter uses approximate methods to integrate the mass-, energy-, and CO2-balance equations. The second model described in the present work is a distributed-parameter model, in the form of a vertical column representing the main upflow zone at Ohaaki. This model produces a good fit to the observed distribution of pressure and temperature with depth in the natural state at Ohaaki and a good match to the observed response of the reservoir during 5 years of experimental production and 3 years of recovery. SPEJ p. 215
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Neves, Orlando Sílvio Caires, Juliana Carolina Alves Horlle, Eduarda Demari Avrella, Luciana Pinto Paim, and Claudimar Sidnei Fior. "Potencial dos substratos pó-de-coco e casca de pinus compostada na promoção de crescimento de mudas de umbuzeiro." Revista Agraria Academica 4, no. 2 (March 1, 2021): 5–12. http://dx.doi.org/10.32406/v4n2/2021/5-12/agrariacad.
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The objective of this work was to evaluate the potential of the processed coconut fiber (coconut powder) and composted pine bark, isolated and in combination, in promoting the growth of umbuzeiro seedlings. This work was conducted in a greenhouse in a completely randomized block experimental design, with five treatments and four replications. The treatments consisted of the following formulations, in volumetric proportions: 100% pine bark (CP); 75% CP + 25% coconut powder (PC); 50% CP + 50% CP; 25% CP + 75% CP and; 100% PC). The coconut powder substrates or the formulation containing 75% coconut powder + 25% composted pine bark provided Imbu seedlings with higher vegetative quality. The lower density, higher total porosity and higher percentage of available water were the physical characteristics of the substrates that most influenced the growth of Imbu seedlings.
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Aguilar-Joo, José Eduardo, Neín Farrera-Vázquez, Selene López-Cameras, Raúl Pavel Ruíz-Torres, and Carlos Alonso Meza-Avendaño. "Influence on the Incorporation of Carbonate Minerals as Stabilizers in Clay and Sawdust-Based Blocks for Thermal Insulation." Buildings 13, no. 3 (March 1, 2023): 656. http://dx.doi.org/10.3390/buildings13030656.
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This research is focused on the influence of carbonate minerals on the properties of ceramic blocks as a replacement for commercial stabilizers, using three types of clays and sawdust as raw materials extracted from Chiapas, Mexico, for their application in thermal insulation on lightweight construction systems of local buildings. The effective thermal conductivity of each sample was tested by the guarded hot plate method in a permanent state, and their physical and chemical properties were determined by water absorption, X-ray powder diffraction, and X-ray fluorescence spectroscopy techniques. The results directed attention toward the knowledge of the role of the parameters in improving the thermal insulation properties, highlighting calcite as a favorable stabilizer in the manufacture of such blocks. Furthermore, the parameter affecting the thermal conductivity of the samples is the mass percentage of magnesium oxide (MgO) in a positive linear trend. Finally, the volumetric proportions of the sawdust as a pore-forming aggregate influence the decrease in the bulk density in the ceramic blocks and, thus, the reduction in the thermal conductivity.
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Bijak, Szymon, and Hubert Lachowicz. "Impact of Tree Age and Size on Selected Properties of Black Locust (Robinia pseudoacacia L.) Wood." Forests 12, no. 5 (May 17, 2021): 634. http://dx.doi.org/10.3390/f12050634.
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Black locust (Robinia pseudoacacia L.) is a non-native tree species that occupies a remarkable area in the forests of western Poland. It is mainly cultivated for the bee-keeping purposes as well as for its high quality wood. We investigated the impact of tree age and diameter on the selected structural, physical and mechanical attributes of wood of black locust that grows in conditions of mesic oligotrophic site. We analysed 200 samples originating from 18 trees that varied with age (38, 60 and 71 years old) and diameter (thin, medium and thick specimen selected according to Hartig’s method). Individual wood properties were determined along with corresponding European or Polish standards. Structural and mechanical attributes were determined for moisture of 12%. We found significant impact of tree age on tree-ring width, latewood proportion, density, oven-dry density, basic density, share of woody substance, porosity, as well as radial, tangential, longitudinal and volumetric shrinkage, compression strength parallel to grain, static bending, coefficient of compression strength parallel to grain and coefficient of static bending. The older the trees, the higher values of individual attributes were observed. In turn, the effect of tree diameter was less profound and no significant impact of that feature was found for latewood proportion, anisotropy and almost all of the shrinkage parameters. Thin trees exhibited the lowest values of the analysed parameters, while medium ones—the highest. In general, the highest technical quality of the investigated wood can be found in the youngest trees, whose wood characterises with the properties significantly exceeding native Polish tree species such as oak or beech.
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Witcher, Anthony L., Jeremy M. Pickens, and Eugene K. Blythe. "Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae." Agronomy 10, no. 4 (April 1, 2020): 484. http://dx.doi.org/10.3390/agronomy10040484.
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Container-grown nursery crops are commonly exposed to root zone stress due to inadequate moisture and supraoptimal root zone temperature (RZT). Compost substrates can improve water and nutrient retention but plant responses can vary due to physical and chemical properties. Dark color containers absorb solar radiation through the container side wall leading to excessive heat buildup in the substrate, yet white containers can reduce RZT. Compost substrates and container color were examined for effects on RZT and growth of “Green Giant” arborvitae (Thuja standishii × plicata “Green Giant”). “Green Giant” arborvitae were transplanted into white or black containers (11.3 L) filled with a pine bark substrate (PB) or PB mixed with compost (C) at two different proportions [PB:C (9:1) and PB:C (7:3)]. White containers reduced maximum RZT by up to 7 °C and RZT remained above 38 °C for only 3% of the time compared to 21% of the time in black containers. Shoot growth increased over 50% in white containers compared to black containers. Compost increased substrate volumetric water content (VWC), increased shoot growth by up to 24%, and reduced total irrigation volume by up to 40%. Utilizing white containers for minimizing RZT and compost-amended substrates to maintain adequate VWC can improve root and shoot growth and overall crop quality while reducing nursery production inputs.
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Pinahin, Igor, Michael Yagmurov, Svetlana Vrublevskaya, and Maria Shpack. "Investigation of the Structure of Hard Alloys That Have Undergone Bulk Pulsed Laser Hardening Using X-Ray Structural Analysis." MATEC Web of Conferences 346 (2021): 02003. http://dx.doi.org/10.1051/matecconf/202134602003.
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The main principles of volumetric pulsed laser hardening method are presented in the article. The results of experiments based on tensometry with further processing using the LabVIEW system are shown. Obtained results confirm the appearance of the mechanical shock wave in materials due to the action of a single high-energy laser pulse. The received dependences were confirmed for hard alloys with different chemical compositions. Using of X-ray structural analysis allowed to establish that various hard alloys processed by pulsed laser hardening characterized by the third kind (nanostructure) changing the structure due to the accumulation of structural defects (sizes of mosaic blocks, crystal microscopic distortions, density of dislocations). It has been established that the third kind changing the structure increases the main service mechanical properties of hard alloys (microhardness, abrasive wear resistance, flexing strength). In addition, it was found that the change in the hard alloys properties is directly proportional to the change in the nanostructure of materials.
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Bouwmeester, Sjoerd, Thomas Mast, Frits Prinzen, Lukas Dekker, and Patrick Houthuizen. "Predictive value of left atrial remodeling for response to cardiac resynchronization therapy." Journal of Ultrasonography 22, no. 90 (July 11, 2022): 168–73. http://dx.doi.org/10.15557/jou.2022.0027.
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Aim: Response to cardiac resynchronization therapy varies significantly among patients, with one third of them failing to demonstrate left ventricular reverse remodeling after cardiac resynchronization therapy. Left atrial size and function is increasingly recognized as a marker of disease severity in the heart failure population. The aim of this study was to evaluate whether echocardiographic left atrial indices predict left ventricular reverse remodeling after cardiac resynchronization therapy. Materials and methods: Ninety-nine cardiac resynchronization therapy candidates were prospectively included in the study and underwent echocardiography before and 3-months after cardiac resynchronization therapy implantation. Cardiac resynchronization therapy response was defined as a 15% relative reduction in left ventricular end-systolic volume. Indexed left atrial volume, left atrial reservoir strain, left ventricular end-diastolic volume, and left ventricular ejection fraction along with other known predictors of cardiac resynchronization therapy response (gender, etiology of heart failure, presence of typical left bundle branch block pattern, QRS duration >150 ms) were included in a multivariate logistic regression model to identify predictors for cardiac resynchronization therapy response. Results: Cardiac resynchronization therapy response occurred in n = 63 (64%) patients. The presence of a typical left bundle branch block (OR 4.2, 95 CI: 1.4–12.1, p = 0.009), QRS duration >150 ms (OR 4.2, 95 CI: 1.4–11.0, p = 0.029), and left atrial volume index (OR: 0.6, 95 CI: 0.4–0.9, p = 0.012) remained the only significant predictors for cardiac resynchronization therapy response after three months. None of the baseline left ventricular parameters showed an independent predictive value. Conclusion: Left atrial size at baseline is an independent predictor and is inversely proportional to left ventricular volumetric reverse remodeling in cardiac resynchronization therapy candidates.
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Londra, Paraskevi A., Angeliki T. Paraskevopoulou, and Maria Psychoyou. "Evaluation of Water–Air Balance of Various Substrates on Begonia Growth." HortScience 47, no. 8 (August 2012): 1153–58. http://dx.doi.org/10.21273/hortsci.47.8.1153.
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The water–air balance of four soilless substrates: 75% sphagnum peat–25% perlite (Ps75:P25), 50% sphagnum peat–50% perlite (Ps50:P50), 50% coir–50% perlite (C50:P50), and a fortified substrate with 60% sphagnum peat–30% black peat–10% perlite (Ps60:Pb30:P10) (in a volumetric proportion) was investigated under two different irrigation methods (drip and sub-irrigation), and its effect on the growth of Begonia ×elatior ‘The President’ was studied. The bulk density, particle size distribution, and water retention curve of the substrates were determined. Furthermore, the water profiles, oxygen (Ο2) concentration, and Ο2 diffusion rate of all substrates were determined during a 16-week cultivation period. Plant height, flower production, and both shoot and root dry weights as well as percent growth increase of plants were measured at the end of the experiment. The substrate water profiles showed that the water content was greater and air content was less in substrates of pots irrigated with drip irrigation than with sub-irrigation. The O2 concentration in all substrates irrespective of the irrigation method was high. The O2 diffusion rate values of sub-irrigated substrates were greater than those drip-irrigated, and Ps60:Pb30:P10 showed the greatest values. Shoot and root dry weights and percent growth increase of drip-irrigated plants were greater than that of sub-irrigated plants.
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Kun, Eva, and Kálmán Marossy. "Effect of Crystallinity on PLA’s Microbiological Behaviour." Materials Science Forum 752 (March 2013): 241–47. http://dx.doi.org/10.4028/www.scientific.net/msf.752.241.
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Recent work describes changes in polylactic acid samples with different crystallinity during microbiological degradation. We treated PLA at 93°C for different periods of time, which yielded samples with particular crystallinity. The fraction of crystalline phase was determined by differential scanning calorimetry, and the visual effect of crystallinity was measured by colorimetric method with black and white backgrounds. The medium for biological degradation process was living sludge under room temperature and normal atmospheric pressure. Furthermore, the change in mass was also measured. The results show that increased crystallinity reduces the rate of mass lost. The volumetric proportion of crystallinity is in direct correlation with opacity, so checking transparency is also a suitable possibility for estimating crystallinity. DSC, colorimetric method and visual observation experiments confirm that crystallinity has increased proportionally by the time of heat treatment and caused opacity. The experiments show that water uptake happened faster and in much higher volume in polymers having dominantly amorphous structure than in the case of samples with higher crystallinity. In the case of materials with only 2.43% crystallinity, weight lost began later because they had a greater water uptake during the first 7-12 days, while this period took only 7 days with a very low water uptake for samples containing approximately 35% crystalline phase. After swelling, weight loss of the crystalline samples was much slower than that of samples containing more amorphous parts, because crystalline phases inhibit the diffusion of small water molecules and the microbes with it.
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Zhang, Yongchun, Haijun Mao, Hao Zhang, Yueli Li, Yanfang Jiang, and Jiarui Li. "Optimization of Acid Fracturing Process for Carbonate Reservoirs in Daniudi Gas Field." Energies 15, no. 16 (August 18, 2022): 5998. http://dx.doi.org/10.3390/en15165998.
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The Daniudi gas field is located in the Ordos Basin’s northern section of the Yishan slope. The intertidal–subtidal depositional environment dominates the lithology of the Ma55 sub-member, resulting in a stable, thick-layered dark gray–gray–black limestone and lime dolomite. The stratum is stable laterally as well as dolomite, with an average thickness of 26.8 m. Fractures, dissolution expansion pores, and inter-crystalline dissolved pores are the primary reservoir space kinds, with a minor number of karst caves and fractures generated as well. The main distribution ranges for porosity and permeability are 1–8 percent and 0.01–1 mD, respectively. Low porosity, tightness, and ultra-low permeability are common characteristics, and a single well typically has no natural productivity. Production stimulation technologies like pre-fluid acid fracturing, compound sand addition acid fracturing, and multi-stage injection + temporary plugging volumetric acid fracturing have been gradually optimized using the horizontal well development method, and breakthroughs in the development of tight and low-permeability carbonate rock reservoirs have been made. However, the conditions of different types of reservoirs are quite different, and the acid fracturing process is not matched and imperfect, resulting in large differences in the productivity of different horizontal wells after fracturing, as well as a high proportion of low-yield wells, which cannot meet the needs of cost-effective and effective development of this type of gas reservoir. In light of the aforementioned issues, a series of laboratory tests have been carried out to explore the stimulation effects of acid fracturing on different types of reservoirs and to optimize the acid fracturing process in the Daniudi gas field. The results show that the rock mechanical performances and the acid etching conductivities of the rock specimens are related to the types of reservoirs. The rock mechanical properties can be deteriorated after acidizing, but different types of reservoirs have different degrees of deterioration. According to the results of acid etching conductivity of different types of reservoirs, conductivities obtained by high and low viscosity and cross-link-gelled acid (two stage injection) processes are higher than those of high viscosity systems. The experimental results of process suitability suggest adopting high and low viscidity acid systems for pore type and fracture-dissolved pore type reservoirs, and cross-linked acid systems for fracture-pore type reservoirs. The findings of this study can help form a better understanding of the performance of different types of reservoirs under the various acidified conditions that can be used for the optimization of acid fracturing processes in carbonate formations.
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Shavelkina, Marina B., Ravil Kh Amirov, Tatyana I. Borodina, Viktor I. Kiselev, Tatiana B. Shatalova, and Kamille S. Rabadanov. "FORMATION OF NANO STRUCTURES IN RESULT OF HOMOGENOUS NUCLEATION OF CARBON OBTAINED IN THERMAL PLASMA UNDER ATMOSPHERIC PRESSURE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 59, no. 8 (July 17, 2018): 27. http://dx.doi.org/10.6060/tcct.20165908.34y.
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Thermal plasma processing of carbon sources using a plasma jet with high heat capacity is one of the most promising methods for the synthesis of new materials. This paper describes the low-temperature deposition of carbon nanomaterials by remote plasma-enhanced chemical vapor deposition (PECVD) in the absence of catalysts. The remote PECVD process differs from conventional and direct PECVD process in two ways: (a) only a subset of the process reactants and/or diluents are directly plasma excited; and (b) thin film deposition takes place on a substrate that is outside of the plasma glow region. In conventional CVD methods, carbon is produced from the decomposition of carbon sources such as hydrocarbons, carbon monoxide, alcohols, and so on, over a metal catalyst. The unavoidable metal species remaining in carbon nanomaterials would lead to obvious disadvantages for property characterization and application exploration. Despite sustained efforts, it is still an intractable problem to remove metal catalysts completely from carbon nanomaterials samples without introducing defects and contaminations. Good reactor design allowed to overcome problems of chemical and structural purity, and poor process robustness in terms of phase composition of product from run to run. For the synthesis of graphene materials, carbon black, carbon nanotubes, nanowires we used the thermal plasma generator which is a high current divergent anode-channel DC plasma torch. The experiment involved a simultaneous input of hydrocarbons (methane, propane, butane, acetylene) with the plasma forming gas (helium, argon, nitrogen) into the plasma torch, wherein heating and decompositions occurred in the plasma jet and in the region of the arc discharge, followed by condensation of the synthesis product on metallic surfaces. The deposition rate was varied with distance from the plasma. Consumption of carbon source, plasma forming gas and plasma torch power were changed independently from each other. For the experimental conditions the electric power of plasma torch was set up to 40 kW. Regularities of formation of carbon thread-like nanostructures and graphene in the course of hydrocarbons pyrolysis in thermal plasma without participation of catalytic particles were studied by means of electron microscopy, X-ray diffraction, IR-spectrometry and thermogravimetry. Depending on the pyrolytic synthesis parameters, different proportions of crystal carbon and soot may be obtained. It has been demonstrated that the phase composition is varied by hydrocarbons flow rate, plasma forming gas pressure and dc plasma torch power. It has been established through the experiments that carbon nucleation is volumetric and proceeds according to the model of explosive soot formation.
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Favero, Silvia, Ifan Erfyl Lester Stephens, and Magda Titirici. "Deconvoluting Transport and Kinetics on Ionic Liquid-Modified Fe Catalysts for Oxygen Reduction." ECS Meeting Abstracts MA2022-01, no. 35 (July 7, 2022): 1471. http://dx.doi.org/10.1149/ma2022-01351471mtgabs.
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Introduction Hydrogen fuel cells could play a key role in the decarbonization of the energy sector. However, their commercialization is hindered by the sluggish kinetics of the oxygen reduction reaction (ORR) and by the requirement of platinum, which is expensive and unsustainable. Alternative catalysts based on transition metals have proven promising, but their activity and durability is still far from that of platinum. Recently, thin layers of ionic liquids have been successfully used to improve both the durability and activity of noble-metal free ORR catalysts[1]. As shown in Figure 1, the presence of the ionic liquid layer can influence the reaction kinetics through multiple effects: (i) O2 transport, (ii) water transport (iii) proton transport and (iv) binding to the reaction intermediate. These competing effects are generally convoluted. To that end, we have recently developed models to quantify the effect of the ionic liquid on both oxygen transport and reaction kinetics. Effect of Ionic liquids on reaction kinetics The ionic liquids tested for oxygen reduction are hydrophobic and their degree of water uptake is largely controlled by the cation. By decreasing the concentration of water at the active sites, they can cause the dehydration of the *OH intermediate, ultimately weakening the *OH bond[2]. For those catalysts such as Pt, which sit on the strong binding side of the volcano, this weakening of OH causes an increase in activity[3]. To the contrary, we have now shown that ionic liquid layers decrease the activity of catalyst on the weak binding side of the volcano, such as iron phtalocyanine (see Figure 2). By changing ionic liquid, we can control hydrophobicity and by monitoring the position of the voltammetric peak for *OH adsorption we can probe the strength of *OH binding. In this way, we are able to confirm the earlier hypothesis that hydrophobicity controls *OH binding[2]. We hence provide a new lever for tailoring the reaction kinetics of oxygen reduction for any transition metal catalyst using ionic liquids. Oxygen Transport in ionic liquid layers The ideal ionic liquid should transport oxygen quickly, while featuring high oxygen solubility. However, it has been shown that O2 solubility and diffusivity cannot be independently tuned, as, for example, fluorination of the anion improves oxygen concentration, at the expense of diffusivity[4]. The optimum balance between these two parameters has been so far unclear. To that end, we have developed a way to deconvolute the effect of oxygen solubility and diffusivity. Using gravimetric, volumetric and electrochemical techniques, we reliably characterized oxygen transport in ionic liquids, and we were able to experimentally distinguish between oxygen activity and concentration. By using Fick’s diffusion and the Faraday law, we obtained a prediction for the diffusion-limited current in a rotating disc-electrode, as a function of the nature of the ionic liquid, its thickness and the rotational speed. As shown in in Figure 3, the diffusion-limited current density correlates to the permeability of oxygen in the ionic liquid layer; with our experimental data confirming the model. When looking at the diffusion-limited region, this model leads to the trivial conclusion that oxygen transport can be improved by maximizing oxygen permeability in the ionic liquid and increasing the thickness to that of the diffusion layer. However, real fuel cell devices are operated at a potential where both oxygen transport and kinetics are rate-limiting. In this case, the reaction rate is proportional to oxygen activity in the ionic liquid. Using the model developed, we were able to conclude that oxygen activity should be maximised over transport and that a single monolayer is the ideal ionic liquid coverage. Finally, we used a sorption analyser to study the ionic liquid distribution on the surface of the catalyst. We observed that rather than forming the ideal monolayer, the ionic liquid fills up the smallest pores first and tends to block bigger pores. Our current work is focusing on improving catalyst wettability by the ionic liquid to approach the ideal distribution. Conclusion In conclusion, the cation and anion of ionic liquids can be independently tailored to control hydrophobicity on one side and O2 activity on the other. This can ultimately allow to optimize the binding energy of key intermediates and maximize the reactant concentration at the active site. Our approach provides a rational method to improve the activity of noble-metal-free oxygen reduction catalysts. [1] Favero et al., Adv. Energy Sustainability Res. 2021, 2, 2000062 [2] Casalongue et al., Nat. Commun., 2013, 4, 2817 [3] Huang et al., J. Electrochem. Soc., 2017, 164, F1448 [4] Vanhouette et al., RCS Adv., 2018, 8, 4525 Figure 1
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Yoshida, Luna, Yuki Orikasa, and Masashi Ishikawa. "Mechanism of Improved Lithium-Sulfur Battery Performance by Oxidation Treatment to Microporous Carbon as Sulfur Matrix." ECS Meeting Abstracts MA2022-02, no. 64 (October 9, 2022): 2299. http://dx.doi.org/10.1149/ma2022-02642299mtgabs.
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1. Introduction Lithium-sulfur (Li-S) batteries are rechargeable devices assembled with a sulfur cathode and a lithium metal anode. Li-S batteries have twice the volumetric energy density and 5 times the gravimetric energy density of lithium-ion batteries (LIB). Hence, Li-S batteries are expected to be applied to stationary power sources and EV vehicles [1]. However, Li-S batteries have the following issues: ・Sulfur and the final discharge product (Li2S) are insulators. ・In the discharge process, sulfur expands up to 1.8 times, so the structure of batteries is unstable. ・Intermediate products (Li2Sx (x = 4 – 8)) dissolve in an electrolyte; Li2Sx (x = 4 – 8) diffused to an anode to provide an insulating layer at the anode surface. ・In the charge process, Li2Sx (x = 4 – 8) causes redox shuttling. As a result, Li-S batteries cannot charge and discharge stably. In order to deal with this problem, Nazar et al. reported the method that sulfur is confined in porous carbon [2]. This approach provides a cathode realizing good electronic conductivity, restriction of sulfur expansion, and suppression of Li2Sx (x = 4 – 8) dissolution. Although these improved characteristics allow Li-S batteries to operate, The discharge capacity of Li-S batteries is still not high enough and this needs to be addressed. In our previous study, we reported that oxidation treatment to microporous carbon (MC) with HNO3 improves Li-S batteries' discharge capacity [3]. Moreover, we clarified that the discharge capacity of Li-S batteries has an approximate proportional relation with the amount of oxygen-containing functional groups on the MC surface [4]. This work attempts to elucidate the mechanism of improved Li-S battery performance by oxidation treatment to MC. Our report would lead to the proposal of a novel strategy to improve the performance of Li-S batteries. 2. Method 2.1 Preparation of Oxidized MC-Sulfur composite (Ox MC-S) MC was added into 69 wt.% HNO3 and refluxed at 120ºC for 2 h. By vacuum filtration and washing with deionized water, Ox MC was obtained. Ox MC dried in vacuum at 80ºC overnight was mixed with sulfur at a weight ratio of Ox MC: S = 48: 52. The mixture was thermally annealed at 155ºC for 5 h (Ox MC-S). Untreated MC was also composited with sulfur by the same method (MC-S). 2.2 Assembling of Cells Each MC-S cathode was prepared by mixing the MC-S, acetylene black, carboxymethyl cellulose, and styrene butadiene rubber at a respective weight ratio of 89: 5: 3: 3 and coating the resulting aqueous slurry on an Al foil current collector. The cells with the MC-S electrode and Li metal foil as an anode were assembled in a glove box filled with Ar. Lithium bis(trifluorosulfonyl)imide (LiTFSI): tetraglyme (G4): hydrofluoroether (HFE) = 10: 8: 40 (by mol) was used as the electrolyte. 2.3 Electrochemical Impedance Spectroscopy (EIS) To elucidate the effect of oxidation treatment on the internal resistance of Li-S batteries, EIS was carried out at various potentials (Discharge 2.0 – 1.0 V and Charge 1.0 – 3.0 V). The obtained Nyquist plots were used for the evaluation of solid electrolyte interphase (SEI) resistance (Rsei), charge-transfer resistance (Rct), and Warburg impedance (Rw). Rw was investigated with the calculation of Warburg coefficient (σ). 3. Major results and conclusion Since oxidation treatment to MC significantly increased the discharge capacity of Li-S batteries [3][4], it was expected that oxidation treatment would lower the internal resistance of Li-S batteries. EIS of MC-S and Ox MC-S at various potentials showed that oxidation treatment reduced Rsei by an average of 12.2 Ω. This indicates that the SEI thickness was reduced, or the SEI was composed of highly ion-conductive components by the oxidation treatment. Rct decreased only at lower potentials, and the Warburg coefficient decreased except at the end of charge and discharge potential. These results suggest that the oxidation treatment decreases overall resistance, but especially SEI resistance and Warburg impedance, which may improve the discharge capacity of Li-S batteries. We will also report the activation energy of Rsei and Rct and mechanism analysis of decreasing Rsei by oxidation to MC. This work was supported by “Advanced Low Carbon Technology Research and Development Program, Specially Promoted Research for Innovative Next Generation Batteries (ALCA-SPRING [JPMJAL1301])” from JST. [1] Y. Guo et al., Angew. Chem. Int. Ed., 52 (2013) 13186. [2] X. Ji et al., Nat. Mater., 8 (2009) 500. [3] S. Okabe et al., Electrochemistry, 85 (2017) 671. [4] L. Yoshida et al., ECS 238th PRiME Meeting Abstracts (2020).
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Mahdevari, Saeed, and Parviz Maarefvand. "Applying ultrasonic waves to evaluate the volumetric block proportion of bimrocks." Arabian Journal of Geosciences 10, no. 9 (May 2017). http://dx.doi.org/10.1007/s12517-017-2999-8.
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Zhang, Han, Daniela Boldini, Lehua Wang, Huafeng Deng, and Chang Liu. "Influence of Block form on the Shear Behaviour of Soft Soil–Rock Mixtures by 3D Block Modelling Approaches." Rock Mechanics and Rock Engineering, February 15, 2022. http://dx.doi.org/10.1007/s00603-022-02795-x.
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AbstractThe influence of block forms on the shear behaviour of soil–rock mixtures with soft blocks (soft S–RMs) can be efficiently investigated by the discrete element method (DEM) on the basis of accurate 3D models accounting for the block breakage. This paper proposes a novel modelling approach, based on the spherical harmonics series, for the generation of 3D block geometries with different forms but same convexity and angularity. An already existing non-overlapping modelling approach was improved, characterized by a reduced computational cost, for the set-up of 3D block DEM models accounting for the block breakage. A number of soft S–RM DEM samples, subjected to numerical direct shear tests, were generated to analyze the influence of block forms and volumetric block proportion VBP on the mesoscopic and macroscopic behaviours. The results showed that the breakage degree is maximum for the spheroidal blocks, followed by the oblate, prolate and blade ones, due to the combined influence of the block frictional sliding and rotation. The shear strength of soft S–RMs is mainly controlled by the block interlocking and breakage, being maximum in the case of spheroidal block samples when the applied normal stress is low and in the case of prolate and blade ones for a high normal stress. It was found that a nonlinear Mohr–Coulomb criterion can provide a good description of the shear strength envelope of soft S–RMs. Soft S–RMs are characterized by a higher friction angle if composed by spheroidal and prolate blocks when the VBP is 40%, due to their elevated block interlocking, and in the case of prolate and blade blocks when the VBP is 60% at the higher normal stress, due to their lower block breakage degree.
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Wang, Shengnian, Xinqun Gao, Honglei Hui, Wei Ma, Chong Shi, and Peng Zhang. "Normalized Shear Modulus and Damping Ratio of Soil–Rock Mixtures With Different Volumetric Block Proportions." Frontiers in Physics 9 (September 28, 2021). http://dx.doi.org/10.3389/fphy.2021.740993.
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The volume fraction of rock blocks plays a particularly significant role in static/dynamic shear behaviors of soil–rock mixtures (SRM). Large-scale cyclic triaxial tests for SRM with different volumetric block proportions (VBPs) were performed at different confining pressures to investigate the reduction of dynamic shear modulus (G) and the increase of damping ratio (λ). Results indicate that VBP has a significant effect on the dynamic behaviors of SRM. The higher VBP is more likely to result in a gentler reduction of G and a faster increase of λ. The variations of dynamic shear modulus ratio (G/G0) and normalized damping ratio (λnor) fall within relatively narrow bands but are very different with gravelly soils and sands due to VBP with particle size larger than 2 mm. The G/G0 and λnor can be characterized by empirical functions about normalized shear strain amplitude (γnor).
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Maheshwari, Ankit, Faye L. Norby, Riccardo M. Inciardi, Wendy Wang, Michael J. Zhang, Elsayed Z. Soliman, Alvaro Alonso, et al. "Abstract 10688: The Association of Atrial Cardiomyopathy with Ischemic Stroke is Minimally Explained by Atrial Fibrillation: The Atherosclerosis Risk in Communities (aric) Study." Circulation 144, Suppl_1 (November 16, 2021). http://dx.doi.org/10.1161/circ.144.suppl_1.10688.
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Introduction: Atrial cardiomyopathy, characterized by abnormalities in left atrial (LA) size and function, is a risk factor for atrial fibrillation (AF) and ischemic stroke. We aimed to determine if 2D-echocardiographic (2DE) LA strain and volumetric parameters are independently associated with ischemic stroke and the extent to which AF mediates this risk in the ARIC study, a community-based cohort study. Methods: We included 4817 ARIC participants (mean age 75; 59% women; 22% Black) and who had 2DE in 2011-13. We evaluated LA volume index (maximum, minimum), LA emptying fraction (total, passive, active), LA strain (reservoir, conduit, contractile). Incident ischemic strokes (2013-2019) were physician adjudicated after review of medical records. AF was ascertained from hospitalization discharge codes and 2-week ambulatory rhythm monitoring in 2016-17. We used multivariable Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals (CI) of LA parameters for stroke and performed mediation analyses to quantify the indirect effect of AF in these associations. Results: After a median follow-up of 5.9 years, each SD increment in LA reservoir stain, LA conduit strain, LA contractile strain, total LA emptying fraction, and active LA emptying fraction was associated with a percent (95% CI) decrease in stroke risk of 27 (14-38), 19 (4-32), 17 (4-29), 19 (6-31), and 14 (1-26), respectively. Greater left atrial minimum, but not maximum volume index was associated with higher stroke risk. The proportion of these associations which was mediated by AF ranged from 3-36%. Our findings remained unchanged in sensitivity analysis excluding participants with AF and on anticoagulants. Conclusions: The associations of LA strain and volumetric parameters with stroke are minimally mediated by AF. Future research should determine whether LA strain and volumetric analysis can guide anticoagulation for stroke prevention in people independent of AF status.
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Wang, Shengnian, Xinqun Gao, Wei Ma, Guoyu Li, Chong Shi, and Peng Zhang. "Empirical Formulas of Shear Modulus and Damping Ratio for Geopolymer-Stabilized Coarse-Grained Soils." Frontiers in Physics 9 (November 25, 2021). http://dx.doi.org/10.3389/fphy.2021.754377.
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The contribution of gravel fraction on the maximum shear modulus (Gmax), dynamic shear modulus ratio (G/Gmax), and damping ratio (λ) of cementitious coarse-grained soils has not been fully understood yet. Large-scale triaxial cyclic tests for geopolymer-stabilized coarse-grained soils (GSCGSs) were conducted with different volumetric block proportions (VBPs) under various confining pressures (CPs) for investigating their dynamic behaviors and energy dissipation mechanisms. Results indicate that the Gmax of GSCGS increases linearly with VBPs but nonlinearly with CP. High VBPs will probably result in a gentle decrease in G/Gmax and a rapid increase in normalized λ (λnor), while the opposite is the case for a high CP. With the shear strain amplitude being normalized, the G/Gmax and λnor are distributed in a narrow band with low dispersion and thus can be well-described by empirical functions of the normalized shear strain amplitude.
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Diederich, Benedict, René Lachmann, Swen Carlstedt, Barbora Marsikova, Haoran Wang, Xavier Uwurukundo, Alexander S. Mosig, and Rainer Heintzmann. "A versatile and customizable low-cost 3D-printed open standard for microscopic imaging." Nature Communications 11, no. 1 (November 25, 2020). http://dx.doi.org/10.1038/s41467-020-19447-9.
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AbstractModern microscopes used for biological imaging often present themselves as black boxes whose precise operating principle remains unknown, and whose optical resolution and price seem to be in inverse proportion to each other. With UC2 (You. See. Too.) we present a low-cost, 3D-printed, open-source, modular microscopy toolbox and demonstrate its versatility by realizing a complete microscope development cycle from concept to experimental phase. The self-contained incubator-enclosed brightfield microscope monitors monocyte to macrophage cell differentiation for seven days at cellular resolution level (e.g. 2 μm). Furthermore, by including very few additional components, the geometry is transferred into a 400 Euro light sheet fluorescence microscope for volumetric observations of a transgenic Zebrafish expressing green fluorescent protein (GFP). With this, we aim to establish an open standard in optics to facilitate interfacing with various complementary platforms. By making the content and comprehensive documentation publicly available, the systems presented here lend themselves to easy and straightforward replications, modifications, and extensions.
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Tambaria, Theodora Noely, Yuichi Sugai, and Ferian Anggara. "Experimental measurements of CO2 adsorption on Indonesian low-rank coals under various conditions." Journal of Petroleum Exploration and Production Technology, September 29, 2022. http://dx.doi.org/10.1007/s13202-022-01569-z.
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AbstractIn this study, the CO2 adsorption capacity was measured on Indonesian low-rank coals in the raw and dry conditions in powder and block states using different coal sample preparation to estimate CO2 sequestration and storage potential. Coal sample specimens were taken from three different areas in the South Sumatra Basin, Indonesia. The adsorption experiments were performed using the volumetric method at a temperature of 318.15 K and pressure up to 3 MPa. The CO2 excess adsorption capacity of powder coal is always higher than block coal. Moreover, decreasing moisture content by the drying process increases CO2 adsorption capacity on coal. Based on fitted CO2 adsorption experimental data with the Langmuir and Freundlich isotherm model, the adsorption occurs on monolayer and multilayer at various conditions. Langmuir volume capacity and pressure show drying and crushing process increased adsorption capacity. However, the drying process affects more the capability of coal to adsorb CO2 than the powdered sample, especially in low-rank coal. It was also observed adsorption capacity is directly proportional to huminite content in the coal. Due to lower moisture and higher huminite contents, the dried WB coal powder had the highest CO2 adsorption capacity over the other coal samples in similar sample conditions. Altogether, this study may provide a better understanding in CO2 adsorption on low-rank coal with different coal sample preparation resulting in different CO2 adsorption capacity.