•Spent coffee grounds and oyster shells particles were employed as fillers.•GGBS-based alkali-activated materials acted as the binders in this study.•Some factors affecting the strength development ...of samples were examined.•The ratio of oyster shells increased, the strength and stiffness increased.•The optimal ratio of oyster shell to spent coffee grounds in mixture was proposed.
This study examined the use of by-product materials such as spent coffee grounds (SCGs), oyster shell (OS), and ground-granulated blast furnace slag (GGBS) for geotechnical applications. To improve the granular skeletons of the highly compressive particles of SCG, the OS were added to a mixture in forms of grinding powder (OS.P) or crushed-granular (OS.G) acting as fill factor in terms of physical interaction, whereas GGBS was only precursor material for alkali-activated materials (AAMs). The OS.P and OS.G were employed at various OS:SCG ratios, by weight. The mixtures were cemented using GGBS-based AAMs activated by a sodium hydroxide solution (SH) and a mixture of sodium hydroxide and sodium silicate (SS). From the test results, several factors that affected the strength development of the samples have been observed, such as the curing time, type of alkaline solution, temperature variation, as well as form and ratio of OS. At the same curing conditions, the SS solution exhibited better strength compared with SH as significant contents of sodium (Na2O) and silicate (SiO2) were provided for the mixture. During the curing period, the temperature variation strongly affected the strength development of the samples. Generally, the strength and stiffness of the samples were improved by the incorporation of SCG with OS.P or OS.G, whereas the slake durability indices were maintained at very high to extremely high values, regardless of the OS type. The maximum unconfined compressive strength (UCS) value reached approximately 2.8 MPa, with optimal ratios of OS.P or OS.G of 0.3 or 0.5, respectively, compared with the SCG weight. At a given ratio, the blend mixture of OS.G and SCG generally exhibited better stiffness and a slightly lower unit weight than OS.P. The mineralogical and microstructure analyses revealed that there was no chemical reaction among SCG, OS.P, and OS.G particles, indicating that these materials act as fillers. In addition, the produced C–S–H gel acts as the dominant binder in this study. Moreover, the excessive addition of OS.P or OS.G caused negative results in strength and durability due to the poor bonding effects between the SCG and OS particles in granular skeletons. Thus, the addition of 50% of OS.G compared with the amount of SCG, by weight, was proposed as the optimal ratio for practical applications.
AbstractChemically induced calcium carbonate precipitation (CCP) using calcium hydroxide (CH) and carbon dioxide (CO2) was employed to clean sand for improving its strength. Joomunjin sand was mixed ...with 2% CH and 10% water, and then cured in a CO2 chamber under 100 or 200 kPa for 2 h. The treatments were repeated 1, 5, and 10 times. At the last treatment cycle, the treated sand was compacted into a mold for testing. A series of unconfined compression and direct shear tests were conducted on the treated sand to evaluate the effects of the CCP on the strength of the clean sand. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis were performed to evaluate the CCP and microstructure of the treated sand. The experimental results indicated that the effect of change in the CO2 chamber pressure on the calcium carbonate content (CCC) was insignificant due to the low pressures applied. As the number of treatments increased from 1 to 10, the CCC increased from 2% to 23%, resulting in increases of the unconfined compressive strength (UCS), and friction angle of treated sand. The efficiency of converting CH to CaCO3 reached 87% after 10 cycles. The UCS increased from 51 to 364 kPa as the number of treatments increased from 1 to 10. The friction angle and cohesion of clean sand also increased from 32° and 0 kPa to 49° and 53 kPa, respectively.
In this paper, we are interested in studying a generalized block space (denoted as
B
φ
p
,
r
) on a space of homogeneous type. We show that this space is the predual of certain generalized ...Morrey–Lorentz space. By duality, we obtain the
B
φ
p
,
r
-bound of operators of Calderón–Zygmund type. In addition, we prove a weak Hardy factorization in terms of commutators of integral operator of Calderón–Zygmund type in block spaces. Thanks to the Hardy factorization result, we obtain a characterization of functions in
BMO
via the boundedness of commutators of homogeneous linear Calderón–Zygmund operators in the generalized block space (resp. the generalized Morrey–Lorentz space). Finally, we study a compactness characterization of commutators of Calderón–Zygmund type in generalized Morrey–Lorentz spaces.
Hypovolemic shock (dengue shock syndrome (DSS)) is the most common life-threatening complication of dengue. We conducted a genome-wide association study of 2,008 pediatric cases treated for DSS and ...2,018 controls from Vietnam. Replication of the most significantly associated markers was carried out in an independent Vietnamese sample of 1,737 cases and 2,934 controls. SNPs at two loci showed genome-wide significant association with DSS. We identified a susceptibility locus at MICB (major histocompatibility complex (MHC) class I polypeptide-related sequence B), which was within the broad MHC region on chromosome 6 but outside the class I and class II HLA loci (rs3132468, Pmeta = 4.41 × 10−11, per-allele odds ratio (OR) = 1.34 (95% confidence interval: 1.23-1.46)). We identified associated variants within PLCE1 (phospholipase C, epsilon 1) on chromosome 10 (rs3765524, Pmeta = 3.08 × 10−10, per-allele OR = 0.80 (95% confidence interval: 0.75-0.86)). We identify two loci associated with susceptibility to DSS in people with dengue, suggesting possible mechanisms for this severe complication of dengue.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This paper develops a discrete-time sliding mode controller with a power rate exponential reaching law approach to enhance the performance of a pneumatic artificial muscle system in both reaching ...time and chattering reduction. The proposed method dynamically adapts to the variation of the switching function, which is based on an exponential term and a power rate term of the sliding surface. Thus, the controlled system can achieve high tracking performance while still obtain chattering-free control. Moreover, the effectiveness of the proposed method is validated through multiple experimental tests, focused on a dual pneumatic artificial muscle system. Finally, experimental results show the effectiveness of the proposed approach in this paper.
In the Bitcoin network, computing double SHA-256 values consumes most of the network energy. Therefore, reducing the power consumption and increasing the processing rate for the double SHA-256 ...algorithm is currently an important research trend. In this paper, we propose a high-data-rate low-power hardware architecture named the compact message expander (CME) double SHA-256. The CME double SHA-256 architecture combines resource sharing and fully unrolled datapath technologies to achieve both a high data rate and low power consumption. Notably, the CME algorithm utilizes the double SHA-256 input data characteristics to further reduce the hardware cost and power consumption. A review of the literature shows that the CME algorithm eliminates at least 9.68% of the 32-bit XOR gates, 16.49% of the 32-bit adders, and 16.79% of the registers required to calculate double SHA-256. We synthesized and laid out the CME double SHA-256 using CMOS 0.18 μm technology. The hardware cost of the synthesized circuit is approximately 13.88% less than that of the conventional approach. The chip layout size is 5:9mm×9mm, and the correctness of the circuit was verified on a real hardware platform (ZCU 102). The throughput of the proposed architecture is 61.44 Gbps on an ASIC with Rohm 180nm CMOS standard cell library and 340 Gbps on a FinFET FPGA 16nm Zynq UltraScale+ MPSoC ZCU102.
AbstractMany regions of the world have witnessed repeated earthquakes that have caused repeated liquefaction of soil. Therefore, the effect of repeated earthquakes on the dynamic behavior of soil is ...an important aspect that must be considered. In this study, a series of cyclic shear loading events and consolidation phases was repeated for loose sand to investigate the cyclic stress–strain response and postcyclic reconsolidation volumetric strain that are usually induced by repeated earthquakes. After an initial consolidation, samples were subjected to repeated cyclic shear loading events and subsequent reconsolidations in a cyclic direct simple shear (CDSS) device with various cyclic stress ratios (CSRs) under undrained conditions for nonliquefied and liquefied stages. Based on the test results, the number of cyclic shear events (Nev), built-up excess pore water pressure ratio (ru), CSR, and maximum double amplitude shear strain (γmaxDA) were shown to be the factors influencing the behavior of samples. For the samples that were not subjected to any prior liquefaction stage, the reliquefaction resistance continuously increased as Nev increased. For those subjected to repeated liquefaction, the samples presented cyclic liquefaction accompanied by high flow shear strain in the first event. The reliquefaction resistance drastically decreased in the second cyclic shear loading event as a result of the critical anisotropy induced by the first cyclic shear loading event when the contraction tendency prevailed. The samples showed cyclic mobility behavior from the fourth event onward, corresponding to the predominance of the dilation tendency. The obtained γmaxDA and εrcV increased as CSR and/or ru increased and decreased as Nev increased. The relative density (Dr) was not a major factor affecting the reliquefaction resistance; however, it might have promoted a lower induced anisotropy level, lower induced γmaxDA, lower εrcV, and the change in behavior of samples from cyclic liquefaction (contraction tendency) to cyclic mobility (dilation tendency). A higher contraction tendency in samples resulted in a higher γmaxDA and εrcV. The shear strain induced in the immediate-past cyclic shear loading event was found to be the main factor affecting εrcV. From the γmaxDA−εrcV relationship, two separate zones were observed, namely (1) noninduced flow shear strain; and (2) induced flow shear strain, regardless of CSR and Nev. Additionally, a relationship between γmaxDA and εrcV was proposed for practical applications.
The Central Highlands of Vietnam is an important Robusta coffee growing region. However, the region is facing climate change impacts from rising temperatures and irregular rainfall, while Vietnamese ...coffee farmers predominantly rely on irrigation from heavily depleted aquifers. To continue productive and sustainable growth, this system requires an innovative approach to meet this hydrological challenge. Here we propose a user-friendly tool, which aims to support coffee farmers’ irrigation decisions, through the Targeted Irrigation Support Tool or ThIRST. ThIRST combines seasonal forecasts, on-farm metrics, and farmer’s expertise. The research comprises baseline (
n
= 400) and endline (
n
= 237) surveys of coffee farmers in Đắk Lắk and Lâm Đồng Provinces. Through the surveys, farmers’ irrigation needs and the applicability of the tool are evaluated. Despite low smartphone usage for farming advisory, the results show the tool allows coffee farmers to continually achieve water-use efficiency and adapt to climate variability. Involving farmers in the design, production and evaluation of climate services can improve the trust and uptake of agro-advisories and the way this information is communicated.
Chemical investigation of the cultured polyspore-derived mycobionts of a Pseudopyrenula subnudata lichen led to the isolation of two new compounds, subnudatones A and B (1 and 2), together with four ...known compounds, 1-(2-hydroxy-1,2,6-trimethyl-1,2,4a,5,6,7,8,8a-octahydronaphthalen-1-yl)ethanone (3), libertalide C (4), aspermytin A (5), and 6,7-dimethoxy-4-hydroxymellin (6). Their chemical structures were elucidated by extensive 1D and 2D NMR analysis and high resolution mass spectroscopy, and comparisons were made with the literature. The absolute configuration of 1 was defined unambiguously using single crystal X-ray crystallography. Compound 1 represents the first dimeric decalin polyketide to be found in nature. The in vitro cytotoxicity of 1 against two cancer cell lines (K562 and MCF-7) was evaluated. Compound 1 showed moderate cytotoxic activity with IC50 values of 23.5 ± 1.0 and 51.9 ± 1.4 μM, respectively.
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