Increase In Substitution Rate Research Articles

A numerical simulation study on the characteristics of wrap shell lightweight aggregate concrete based on random aggregate model

It is a way to reuse solid waste by using dredged silt as raw material to prepare unburned wrap shell lightweight aggregates and replacing crushed stone aggregate to prepare unburned wrap shell lightweight aggregates concrete specimen. In order to understand the characteristics of wrap shell lightweight aggregates concrete, this paper adopts the method of combining laboratory test and numerical simulation to design the mix ratio test scheme of concrete specimens with different substitution rates of wrap shell aggregate (0 %, 25 %, 50 %, 75 %, 100 %), and conducts indoor mechanical properties test and numerical simulation simulation test on them, so as to obtain and analyze the mechanical properties and failure characteristics.The results show that:(1) The peak stress intensity of concrete specimens decreases linearly with the increase of the substitution rate of wrap shell aggregate.(2) The peak stress of concrete under different wrap shell round aggregate substitution rates is normally distributed, and the dispersion of peak strength decreases with the increase of wrap shell aggregate substitution rate. When the substitution rate is 0 %, the dispersion of peak strength is the largest.(3) Under the uniaxial compression simulation test, the failure mode of concrete specimens changes with the addition of the substitution rate of wrap shell aggregate. When the crack failure occurs, natural coarse aggregate with high strength is chosen to bypass, while when it comes to wrap shell aggregate with low strength, it is chosen to penetrate. With the continuous addition of round aggregate, the stress concentration phenomenon inside concrete can be effectively improved and the number of micro-cracks can be reduced.But at the same time, the penetration cracks gradually increase and gradually tend to be straight.The fractal dimension is negatively correlated with the compressive strength and positively correlated with the substitution rate of wrap shell aggregate.The above research can provide theoretical basis for the popularization of recycled concrete with wrap shell aggregate.

Physical properties of cement composite with monoethanolamine

This study analyzed the fluidity, air content, flexural strength, compressive strength and carbon dioxide adsorption performance of cement, furnace slag and fly ash-based cement composite using appropriate substitution values of MEA derived from preliminary experiments. Fluidity and air content were found to increase as the fly ash substitution rate increases. It is believed that the increases are due to the fly ash ball bearing effect in combination with the creation of micropores by MEA. The compressive strength was found to decrease with lower furnace slag substitution ratios. This is believed to have resulted because the Pozzolanic reaction of the fly ash plays a more dominant role in determining the compressive strength than does the latent hydraulic activity of furnace slag as the furnace slag substitution rate is decreased. It is determined that the compressive strength was reduced because the Pozzolanic reaction reduces the density of the texture and pore structure of the interfacial transition zone. Carbon dioxide values increase as the furnace slag substitution rate was increased.

Development of eco-friendly engineered cementitious composites (ECC) with both waste glass powder and aggregate: A comprehensive investigation

This study investigated the micro-macro properties of engineered cementitious composites (ECC) with both waste glass powder (WGP) and waste glass aggregate (WGA) as substitutes for binder and silica sand, aiming to achieve sustainable ECC materials and recycle waste glass in a high-value approach. The results indicate that a high volume of WGP used as a replacement for cement leads to a loose microstructure in ECC, whereas ECC prepared with 100 % WGA replacing silica sand exhibit a better microstructure compared to the reference ECC. Replacing cement with a high volume of WGP reduces the compressive and flexural strengths, but replacing silica sand with WGA increases the compressive and flexural strengths of ECC. Under tensile loading, both WGP replacing binders and WGA replacing silica sand enhance the strain capacity of ECC at substitution rates not exceeding 25 %. As the substitution rate increases, replacing 50 % of cement with WGP reduces the strain capacity and ultimate tensile strength of ECC by 18 % and 32.5 %, respectively. Nevertheless, substituting WGA for silica sand can enhance the strain capacity of ECC. Substituting WGP for the binders increases the transport properties and water-permeable porosity of blended ECC, while the replacement of silica sand with a moderate dosage of WGA reduces the water transport properties and water-permeable porosity. The simultaneous substitution of binder and silica sand with WGP and WGA, respectively, enables the production of sustainable ECC with desirable micro-macro properties. The complete replacement of silica sand and fly ash with WGA and WGP, respectively, is feasible, whereas the substitution of cement with a high-volume WGP should be limited.

Partial substitution of wheat flour with kiwi starch: Rheology, microstructure changes in dough and the quality properties of bread

Kiwi starch (KS) is a new fruit-derived starch-based food material. In this study, wheat flour was partially replaced with 10–20% KS to make bread, and the influence of this substitution on mixed flour, dough processing performance, bread quality, and shelf life was investigated. KS substitution improved the water-binding ability of mixed flour, making it easier to gelatinize while improving viscoelasticity but reducing the integrity of the dough's gluten network structure. As the substitution rate increases, the hardness, air-cell ratio, and width-to-height ratio of bread significantly increased, while the springiness, resilience, baking loss, and specific volume reduced significantly (p < 0.05). KS enriched the bread's color and flavor by promoting the Maillard reaction during baking. Overall acceptability of 10% KS group was highest in sensory evaluation. KS substitution significantly reduced starch digestibility and expected glycemic index (GI), inhibited mold growth and reproduction during storage and prolonged the shelf life of the bread at 25 °C.

Genome-wide analysis reveals the contributors to fast molecular evolution of the Chinese hook snout carp (Opsariichthys bidens)

Variations in molecular evolutionary rate have been widely investigated among lineages and genes. However, it remains an open question whether fast rate of molecular evolution is driven by natural selection or random drift, and how the fast rate is linked to metabolic rate. Additionally, previous studies on fast molecular evolution have been largely restricted to concatenated matrix of genes or a few specifically selected genes, but less is known for individual genes at the genome-wide level. Here we addressed these questions using more than 5000 single-copy orthologous (SCO) genes through comparative genomic and phylogenetic analyses among fishes, with a special focus on a newly-sequenced clupeocephalan fish the Chinese hook snout carp Opsariichthys bidens. We showed O. bidens displays significantly higher mean substitution rate and more fast-evolving SCO genes (2172 genes) than most fishes studied here. The rapidly evolving genes are enriched in highly conserved and very basic functions such as translation and ribosome that are critical for biological fitness. We further revealed that ∼25 % of these fast-evolving genes exhibit a constant increase of substitution rate from the common ancestor down to the present, suggesting a neglected but important contribution from ancestral states. Model fitting showed that ∼85 % of fast-evolving genes exclusive to O. bidens and related species follow the adaptive evolutionary model rather than random-drift model, and 7.6 % of fast-evolving genes identified in O. bidens have experienced positive selection, both indicating the reflection of adaptive selection. Finally, metabolic rate was observed to be linked with substitution rate in a gene-specific manner. Overall, our findings reveal fast molecular evolution of SCO genes at genome-wide level in O. bidens, and uncover the evolutionary and ecological contributors to it.

Evolution and virulence of porcine epidemic diarrhea virus following in vitro and in vivo propagation

Practice of inoculating porcine epidemic diarrhea virus (PEDV) in piglets generating feedback material might influence the genetic evolution and attenuation of PEDV. The study was conducted to evaluate evolutionary rate and attenuation following serial in vitro and in vivo propagation. In the study, PED-JPFP0-PJ, Passage 0 (P0), was isolated from infected pigs and serially passaged in Vero cells for 5 consecutive times, P1-P5. P0, P2 and P5 were then subjected to orally inoculate 3-day-old piglets. At 24 h post inoculation, intestines of each passage (F1), were collected, and subsequently sub-passaged in piglets for 2 additional passages (F2-F3). Virus titration, PEDV genomic copies number, VH:CD ratios, and immunohistochemistry were evaluated. S and ORF3 genes were characterized. The results of the study demonstrated that virus titer and virulence were negatively correlated with increased passages, both in vitro and in vivo. Increased substitution rate was observed in higher passages. The evolutionary rate of S gene was higher than that of ORF3. Seven aa changes at positions 223, 291, 317, 607, 694, 1114 and 1199, with reduced N-linked glycan were observed in P5F3. In conclusion, serial passage of PEDV, both in vitro and in vivo, influence the genetic development and the attenuation of PEDV.

Demand forecast information sharing with manufacturer encroachment

This study explores the interplay between the manufacturer’s encroachment strategy and the retailer’s information sharing strategy in a supply chain, wherein both the upstream manufacturer and downstream retailer possess private demand forecast information. The manufacturer has the option to establish a direct selling channel to encroach on the end market, and the retailer can decide whether to share private information with the manufacturer. We consider four scenarios and derive the corresponding equilibrium outcomes of firms. Theoretical research results show that when the manufacturer opts not to encroach, neither the manufacturer nor the retailer will voluntarily share their demand information. In contrast, if the manufacturer encroaches, they will reach an information sharing agreement under certain conditions. Once such an agreement is reached, the manufacturer can benefit more from encroachment. If information sharing is not achieved, the manufacturer encroaches only if his unit direct selling cost is lower than a certain threshold. In addition, fierce competition among channels encourages the manufacturer to encroach. Based on the abovementioned works, we conduct numerical studies to analyze the impact of forecast accuracy on the profits and information sharing value of the manufacturer, the retailer and the whole supply chain. These results offer valuable management insights for firms. For example, the improved forecast accuracy is beneficial to both firms. Moreover, as the channel substitution rate increases, not only the possibility of manufacturer encroachment increases, but both the manufacturer and the whole supply chain also get more profits from it.

Crack development and fracture performance of Recycled Powder Engineered Cementitious Composites (ECC): Experimental investigation

In this paper, recycled concrete powder (RCP) and recycled brick powder (RBP), with particle sizes ranging from 10 to 130 μm, are used to completely replace the fine aggregate quartz sand at a ratio of 1:1. On this basis, recycled glass powder (RGP), with a discussed particle sizes range of 38–300 μm, is used to partially substitute the cementitious materials. Polyethylene (PE) fibers are used as the reinforcement in the Engineered Cementitious Composites (ECC). Using the particle size range and substitution rate of RGP as variables, the crack development, crack mouth opening displacement (CMOD), fracture toughness and fracture energy of Recycled glass powder ECC (RGP-ECC) were discussed through a three-point bending experiment on a single-edge notch beam. A relatively comprehensive evaluation was made on the fracture performance and behavior of recycled ECC, and a suitable mix ratio of recycled powder ECC was given. The results show that the addition of various recycled powders will not affect the multi-slit cracking behavior of ECC, and the cracks can still spread densely, giving the specimen greater deformation capacity and CMOD. The total substitution of fine aggregate by RCP and RBP has a positive impact on the fracture toughness KICini, KICun and fracture energy (GF), but the addition of RGP has some minor negative effects. Among the particle size range and substitution rate of RGP, the influence of substitution rate is more obvious, and the fracture performance will show a downward trend after growth as the substitution rate increases. Choosing the appropriate RGP substitution rate and particle size range can maximize the recycling of construction waste while ensuring fracture performance.

Mechanical performance of low-carbon ultra-high performance engineered cementitious composites (UHP-ECC) with high-volume recycled concrete powder

Reusing recycled concrete powder (RCP) from construction waste for ultra-high performance engineered cementitious composites (UHP-ECC) markedly enhances its sustainability. This paper explores the mechanical properties and environmental benefit of low-carbon UHP-ECC containing high-volume RCP as the replacement of cement, ground granulated blast furnace slag (GGBS) and silica sand. The results indicate that UHP-ECC has a loose microstructure when a high percentage of cement is replaced with RCP, while replacing silica sand with RCP results in a denser microstructure. Substituting 75% of cement with RCP reduces the compressive strength and flexural strength of UHP-ECC by 24% and 17.6%, respectively. Substituting RCP for silica sand and GGBS does not significantly affect the compressive strength of UHP-ECC, albeit slightly reducing its flexural strength. Under the application of uniaxial tensile loading, the introduction of RCP improves the ductility of UHP-ECC at a 25% substitution rate, whether replacing silica sand or binder materials. However, as the substitution rate increases, replacing cement and silica sand with RCP decreases the ductility of UHP-ECC. Specifically, reductions of 10% and 7.6% in ultimate tensile strain are discerned when substituting 75% of cement and 100% of silica sand with RCP in UHP-ECC, respectively. Conversely, substituting a large volume of GGBS with RCP can further enhances the ductility of UHP-ECC, with an 15.5% increase in ultimate tensile strain when replacing all GGBS with RCP. By adjusting the RCP content to serve as an alternative to traditional binders and sand, it is possible to achieve a more sustainable UHP-ECC characterized by ideal mechanical strength and ductility, and RCP-blended UHP-ECC demonstrates favorable environmental and economic benefits.

Damage and Deterioration Mechanism of Coal Gangue Mixed Pumice Aggregate Concrete Under Freeze–Thaw Cycles

The world is facing the problem of depletion of natural sand and gravel resources, and a large amount of coal gangue solid waste is produced in Inner Mongolia, China, which has low utilization rate and causes ecological pollution. In order to improve the gangue in the mining infrastructure construction of a wide range of application prospects, the use of coal gangue as the coarse aggregate of pumice concrete is of great significance. Inner Mongolia is a cold region, and gangue mixed aggregate concrete (MFC) will certainly face the damage caused by freeze–thaw cycles. Therefore, design gangue by different volume replacement rate (0%, 20%, 40%, 60%, 80%,100%) to replace pumice coarse aggregate. The results show that with the increase of gangue substitution rate, the mass loss rate, relative dynamic elastic modulus, and peak stress of MFC decrease, but the trend of peak strain increases. It is mainly attributed to the less Al2O3 and SiO2 content of gangue, which makes the MFC hydration products decrease with the increase of substitution rate and more original microcracks and pores in the specimens. In addition, the damage model of MFC was established by using Weibull statistical distribution theory and the principle of LEMAITRE equivalent effect variation assumption, and the damage evolution characteristics were explored by combining the experimental results. It can provide the theoretical basis for the application of MFC in cold regions.

Study on failure characteristics of baking-free bricks with wrap-shell aggregate

Using sediment at the bottom of rivers and lakes as raw materials to prepare non-fired wrap shell aggregate (WSLAs) and using wrap shell aggregates to replace natural crushed stones to prepare baking-free bricks is a means of resource utilization. In this paper, using harmless treated sludge and other cementitious material mix as the core and cement as the shell, the wrap shell aggregate baking-free bricks were prepared and its damage characteristics were studied. By means of physical test and image processing, the mechanical properties of the baking-free brick under different aggregate substitution rate and grading conditions were analyzed. At the same time, the existing image analysis method is compared to select the most suitable method to study the damage characteristics of the baking-free brick, and further explore the meso-mechanism of the baking-free brick and the development and evolution of the crack under different substitution rates. The main research contents and conclusions are as follows: (1) Based on image processing technology, Multifractal spectroscopy and Grey Level Co-occurrence Matrix are faster, lower cost, and more accurate image analysis methods. These two methods make the development and evolution of cracks more convincing through quantitative analysis when exploring the damage characteristics of the wrap shell aggregate baking-free brick. (2) The fracture width Δa, maximum peak value and Δf are linear with the substitution rate, indicating that with the increase of the substitution rate, the fracture diversity is higher, the fracture complexity is higher, and the fracture propagation is wider and richer. (3) When GLCM analysis is used, the correlation between fracture characteristic values and the substitution rate is also linear, and the results show that the energy and correlation decrease with the increase of WSLAs substitution rate. Entropy and contrast increase with the increase of WSLAs substitution rate. (4) Both multifractal spectrum and gray level co-occurrence matrix can well reflect the fracture characteristics under different CAWS substitution rates. From the perspective of fracture complexity, the entropy linear correlation degree of gray level co-occurrence matrix is better than that of multifractal spectrum, which can simply and intuitively reflect the fracture expansion degree. The grayscale level co-existence matrix divides the crack expansion form into four different levels for more detailed research. For crack propagation, the two methods can be compared and verified at the same time to provide reference value for further engineering applications.

The Broken Chloroplast Gene Clusters in Gymnosperms Exhibit Elevated Substitution Rates

Plant chloroplast (cp) gene clusters consist of genes arranged closely together on the cp genome. These genes are organized in operon structures and participate in cotranscription, typically exhibiting conservation. Broken gene clusters have been observed in gymnosperms. In order to investigate whether the substitution rates and selection pressure of associated genes are affected following the disruption of gene clusters, the cp genomes of 80 species (78 gymnosperms and 2 outgroups) were analyzed. A phylogenetic analysis was conducted using 58 shared genes to examine the evolutionary rates and selection pressure of genes associated with gene clusters and protein-coding genes in Sciadopitys verticillata. The results demonstrate that S. verticillata exhibited the highest number of rearrangements compared to the Cycas revoluta genome. Four gene clusters (rps2, psbB, rpoB, and petL clusters) in S. verticillata were disrupted, while rps2 in Callitris rhomboidea experienced disruption. Significantly increased evolutionary rates were observed in 12 out of 18 gene cluster-related genes in S. verticillata. Following disruption, S. verticillata and C. rhomboidea exhibited an increase in gene cluster-related genes, particularly rps2, and higher selection pressure on both rps2 and atpA genes compared to other species. Furthermore, among the 58 genes shared by S. verticillata, the evolutionary rates of 36 genes increased, and the selection pressure on 13 genes exceeded that of other species. These results indicate an increased substitution rate of gene clusters in S. verticillata and C. rhomboidea. The large-scale rearrangement and elevated substitution rates of the cp genome in S. verticillata were revealed. This study sheds light on the heterogeneity of cp genome evolution in gymnosperms.

Enrichment of a local sourdough bread with zinc and selenium through the use of biofortified whole wheat flour

SummaryIn this study, obtaining sourdough bread enriched in zinc (Zn) and selenium (Se) with biofortified whole wheat flour (BWWF) was investigated. Sourdough bread flour was blended with BWWF in the ratios of 25:75, 50:50 and 75:25. The Zn and Se contents varied from 12.06 to 43.06 mg/kg and from 80.73 to 267.58 μg/kg in the substituted flours (SFs), respectively. Gluten‐quality‐related technological and rheological properties of SFs were also determined. The BWWF negatively affected those parameters, and GlutoPeak torque before maximum and peak maximum time, alveograph energy and extensibility, sedimentation volume, gluten index and lactic acid solvent retention capacity values decreased substantially to 21.0 GPU, 27.5 s, 85.67 10−4 × J, 18.0 mm, 33.33 mL, 81.98% and 78.72%, respectively. The Zn contents of the SFs bread varied between 10.48 and 43.88 mg/kg, and the Se contents were found between 55.7 and 224.3 μg/kg. At 75% replacement, the recommended daily allowance (RDA) was obtained at 33.3% and 36.0% for selenium in adults, respectively, while it was 27.1% for zinc and 25.6% for selenium at the 50% substitution level. With the increase in substitution rates, the volumes of the SFs breads decreased from 337.5 to 516.3 mL, their organoleptic properties deteriorated, and the hardness of the breads increased from 507.5 to 3633.1 g. In the study, the whiteness index (WI) value was higher in the A yeast combination breads. The sensory properties of pore structure, taste and chewiness of the 25% substitution SFs bread were close to those of the control. Compared with control bread, all SFs bread had statistically higher (P &lt; 0.01) ash, protein, total phenolic contents and antioxidant activity (ranging from 1.893% to 2.495%, 8.22% to 11.60%, 75.85 to 117.74 mg GAE/100 g and 8.84 to 13.34 inhibition%, respectively).

Influence of Brick Powder with Different Replacement Ratio on Concrete Performance and its Microscopic Mechanism

Due to the shortcomings of waste bricks, they cannot be used repeatedly. The brick powder can partially replace cement for construction production, which can solve the problem of cement energy consumption. This paper studies the influence of brick powder on the performance of cement-based materials. The research shows that the water absorption effect of brick powder and the friction force are the two main factors affecting concrete. Energy dispersive spectrometer, inductively coupled plasma mass spectrometry and compressive strength tests show that the addition of brick powder leads to the increase of silicon/calcium. inductively coupled plasma mass spectrometry shows that although brick powder dissolves in the early stage, the volcanic ash effect is weak. The results of mercury intrusion porosimetry and ultrasonic pulse velocity are consistent with the compressive strength. When 5 % is added, it shows excellent durability. In addition, with the increase of age, the durability will not decrease significantly. Since the brick powder only needs to be ground to avoid the related process of cement, good economic and environmental benefits can be obtained with the increase of substitution rate.

Mitochondrial Genome Evolution in Annelida-A Systematic Study on Conservative and Variable Gene Orders and the Factors Influencing its Evolution.

The mitochondrial genomes of Bilateria are relatively conserved in their protein-coding, rRNA, and tRNA gene complement, but the order of these genes can range from very conserved to very variable depending on the taxon. The supposedly conserved gene order of Annelida has been used to support the placement of some taxa within Annelida. Recently, authors have cast doubts on the conserved nature of the annelid gene order. Various factors may influence gene order variability including, among others, increased substitution rates, base composition differences, structure of noncoding regions, parasitism, living in extreme habitats, short generation times, and biomineralization. However, these analyses were neither done systematically nor based on well-established reference trees. Several focused on only a few of these factors and biological factors were usually explored ad-hoc without rigorous testing or correlation analyses. Herein, we investigated the variability and evolution of the annelid gene order and the factors that potentially influenced its evolution, using a comprehensive and systematic approach. The analyses were based on 170 genomes, including 33 previously unrepresented species. Our analyses included 706 different molecular properties, 20 life-history and ecological traits, and a reference tree corresponding to recent improvements concerning the annelid tree. The results showed that the gene order with and without tRNAs is generally conserved. However, individual taxa exhibit higher degrees of variability. None of the analyzed life-history and ecological traits explained the observed variability across mitochondrial gene orders. In contrast, the combination and interaction of the best-predicting factors for substitution rate and base composition explained up to 30% of the observed variability. Accordingly, correlation analyses of different molecular properties of the mitochondrial genomes showed an intricate network of direct and indirect correlations between the different molecular factors. Hence, gene order evolution seems to be driven by molecular evolutionary aspects rather than by life history or ecology. On the other hand, variability of the gene order does not predict if a taxon is difficult to place in molecular phylogenetic reconstructions using sequence data or not. We also discuss the molecular properties of annelid mitochondrial genomes considering canonical views on gene evolution and potential reasons why the canonical views do not always fit to the observed patterns without making some adjustments. [Annelida; compositional biases; ecology; gene order; life history; macroevolution; mitochondrial genomes; substitution rates.].

Mechanical Properties and Microstructure Analysis of Cement Mortar Mixed with Iron Ore Tailings

In order to study the feasibility and sand substitution mechanism of cement mortar mixed with iron ore tailings (IOT), iron ore tailings cement mortars (referred to as IOTC) with IOT content of 0%, 25%, and 50% were made and tested. First, the basic properties of IOT used were measured to verify the theoretical feasibility. Second, the uniaxial compressive and tensile strengths, as well as the crack resistance performance of IOTC under different curing ages and different sand substitution rates were tested. Third, the techniques of inductively coupled plasma atomic emission spectrometry (ICP-OES), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS) were used to study the influence of curing age and different sand substitution rates on the chemical, mineralogical, and microstructural characteristics of IOTC. The sand substitution mechanism of IOT was then discussed. The research results proved the feasibility of using IOT to substitute standard sand in cement mortar. Within substitution rate of 0–50%, the mechanical properties increased with the increase of substitution rate. Though limited chemical effects were found by adding IOT, in comparison with standard sand mortar, more hydration products were found and the pore size distribution was changed for IOTC, which corresponds to its mechanical improvement.

Effect of Particle Size and Dosing of Polymeric Aluminum Chloride Waste Residue on Cement Mortar

Five particle sizes and six dosages of polymerized aluminum chloride (PAC) residue were taken to prepare polymerized aluminum chloride residue cement mortar (PACRM). The compressive and flexural strengths were tested, and SEM analysis was performed. The results showed that the change pattern of strength of PAC waste residue mixed into cement mortar was similar to that of fly ash at the same substitution rate. However, the strength of PACRM decreased with the increase of substitution rate. The flexural and compressive strengths of PACRM reached their peak at all ages after replacing cement with PAC waste residue with particle size of 0-0.075 mm and 30% doping. Their strength ratios were greater than 62%. It does not contribute much to the early strength development of PACRM, but contributes more to the later strength development after the cement is replaced by PAC waste residue. PAC waste residue mainly acts as microaggregate and fills into the mortar pores at low substitution rate. The cracks of the matrix structure are filled by C-S-H, so the mortar structure is more dense and the material strength is enhanced. When the substitution rate increases, the water requirement of mortar increases, resulting in an uncompact structure. The internal pores increase after hardening, and the mortar strength decreases rapidly.

Pricing and Distribution Strategies of Fresh Agricultural Product Supply Chain considering Substitutes

In this article, we study the distribution, ordering, and pricing strategies when the supplier has a limited output and the retailer has substitute suppliers in a fresh agricultural product supply chain. The Stackelberg game method is adopted to study the optimal strategy of suppliers and retailers with suppliers as the leader and retailers as the follower. The results show that the wholesale price and selling price of suppliers are related to the price of substitutes and the substitution rate, the wholesale price and online selling price increase when the retailer introduces high-quality substitutes. When substitutes exist, the supplier is willing to distribute more fresh agricultural products to retailers. As the substitution rate increases, suppliers are willing to distribute more quantities. Therefore, retailers should choose more suppliers and fresh agricultural products with a higher substitution rate.

Genomes of leafy and leafless Platanthera orchids illuminate the evolution of mycoheterotrophy

To improve our understanding of the origin and evolution of mycoheterotrophic plants, we here present the chromosome-scale genome assemblies of two sibling orchid species: partially mycoheterotrophic Platanthera zijinensis and holomycoheterotrophic Platanthera guangdongensis. Comparative analysis shows that mycoheterotrophy is associated with increased substitution rates and gene loss, and the deletion of most photoreceptor genes and auxin transporter genes might be linked to the unique phenotypes of fully mycoheterotrophic orchids. Conversely, trehalase genes that catalyse the conversion of trehalose into glucose have expanded in most sequenced orchids, in line with the fact that the germination of orchid non-endosperm seeds needs carbohydrates from fungi during the protocorm stage. We further show that the mature plant of P. guangdongensis, different from photosynthetic orchids, keeps expressing trehalase genes to hijack trehalose from fungi. Therefore, we propose that mycoheterotrophy in mature orchids is a continuation of the protocorm stage by sustaining the expression of trehalase genes. Our results shed light on the molecular mechanism underlying initial, partial and full mycoheterotrophy.

Mechanical Behavior of Concrete Prepared with Waste Marble Powder

Marble production and processing generates a large amount of marble powder waste that has great potential for cementitious material. This paper investigates the application of waste marble powder with different replacement ratios of cement in concrete and experimentally studies the physical and mechanical properties of this green concrete type. Artificial marble powder and original marble powder are used at different replacement levels. The effect of different kinds of marble powder and its replacement ratio on the mechanical properties of concrete are discussed. The results show that the compressive strength, splitting tensile strength, and flexural strength change significantly when the substitution rate of marble powder exceeds 10%; the strength decreases as the substitution rate increases. The usage of artificial marble powder plays a weakening role on concrete performance due to its resin composition when compared to the performance using original marble powder. The stress–stain curves of the two types of marble powder concrete are compared. For concrete, by using the original marble powder, the variation of strain value is not obvious when the marble powder replacement ratio is less than 20%, but for concrete by using artificial marble powder, the peak and ultimate strain decrease significantly with the replacement ratio of marble powder increase.