The material ratio of roadside backfill body based on spatiotemporal law of ground pressure: a case study of Xingtai Mine, China

The material ratio of the roadside backfill body in gob-side entry retaining determines its mechanical properties, which plays an important role in the supporting effect of the roadway surrounding rock. In this paper, a similar material modeling is used to verify the spatiotemporal law of the ground pressure in the engineering case of dense solid backfilling mining in Xingtai Mine, China. Based on that law, the theoretical requirements for the bearing performance of the roadside backfill body are proposed. Finally, a material ratio that meets the theoretical requirements is obtained by compression test, and the deformation and failure characteristics of the backfill body with this ratio are analyzed. The results show that the maximum pressure of the backfill body measured in Xingtai Mine is 5.5 MPa, which is about 40 m away from the coal face, after 40m, the pressure of the backfill body will not increase anymore. The similar simulation test also proved that the ground pressure behind the coal face increases gradually and tends to be stable during the backfilling process, which shows certain spatiotemporal characteristics. Through the proportioning experiment, it is determined that the optimal material ratio of the roadside backfill body is gangue: fly ash: cement = 10:3:1, which meets the theoretical requirement that the strength of the roadside backfill body at any position is not less than the ground pressure at that position. The research results provide a reference for the engineering practice of gob-side entry retaining in dense backfilling mining.

Tunnel Squeezing Deformation Control and the Use of Yielding Elements in Shotcrete Linings: A Review

Shotcrete lining shows high resistance but extremely low deformability. The utilization of yielding elements in shotcrete lining, which leads to the so-called ductile lining, provides a good solution to cope with tunnel squeezing deformations. Although ductile lining exhibits great advantages regarding tunnel squeezing deformation control, little information has been comprehensively and systematically available for its mechanism and design. This is a review paper for the purpose of summarizing the development history and discussing the state of the art of ductile lining. It begins by providing a brief introduction of ductile lining and an explanation of the importance of studying this issue. A following summary of supporting mechanism and benefits of ductile lining used in tunnels excavated in squeezing ground conditions is provided. Then, it summarizes the four main types of yielding elements applied in shotcrete lining and introduces their basic structures and mechanical performances. The influences of parameters of yielding elements on the supporting effect are discussed and the design methods for ductile lining are reviewed as well. Furthermore, recommendations for further research in ductile lining are proposed. Finally, a brief summary is presented.

The Rationality of Compiling a Forest Resource Balance Sheet

The existing forest resource accounting system is limited to the valuation of wood and forest products; the service value of the forest resource ecosystem is not yet included. This study adopts an empirical approach to studying the rationality and influencing factors of compiling a forest resource balance sheet (FRBS). An FRBS can systematically reflect the contribution of forest resources to the economy, ecology, and society in terms of both physical quantity and value quantity. A questionnaire survey was used to collect the data. We found that the determination and measurement of forest resource assets and liabilities and the calculation of the service value of the ecosystem had a supporting effect on the rationality of compiling an FRBS. This study expands the field and scope of forest resource accounting, facilitates the compilation of natural resources and government balance sheets, and presents the practical significance for the theory and practice behind the development of an FRBS.

Effects of Whole-Grain and Sugar Content in Infant Cereals on Gut Microbiota at Weaning: A Randomized Trial

The introduction of complementary foods during infancy marks an important step in the development of the infant gut microbiome. Infant cereals are popular weaning foods but consistent evidence on their effect on the intestinal microbiota, especially when differing in nutritional quality, is lacking. Fecal samples from 4–7-month-old Spanish infants who consumed infant cereals differing in whole grain and sugar content as first weaning foods were analyzed on changes in microbial composition by massively parallel sequencing of the 16S ribosomal RNA gene at baseline and after 7 weeks of intervention. Samples were obtained from a previous trial conducted in Spain demonstrating whole-grain cereal acceptability. In total, samples of 18 infants consuming 0% whole grain cereals with 24 g sugar (0-WG) and 25 infants consuming 50% whole grain cereals with 12 g sugar (50-WG) were analyzed. Microbial composition changed significantly over time (p = 0.001), per intervention group (p = 0.029) and per infant (p = 0.001). Abundance of genus Veillonella increased in both groups while Enterococcus decreased. Within the 0-WG group, phylum Actinobacteria decreased along with genus Bifidobacterium. In the 50-WG, we observed an increase in Lachnoclostridium and Bacteroides. In addition, 50-WG decreased Proteobacteria and Escherichia to levels lower than 0-WG. Although weaning itself appeared to be responsible for most changes, the increased presence of anaerobic fermenters together with inhibition of pathogenic Escherichia may indicate a supporting effect of infant cereals with 50% whole grains and a reduced sugar content over infant cereals manufactured with refined hydrolyzed flours on the infant microbiota. In fact, using a novel methodology for the identification of microbial signatures, we found two groups of microbial taxa predictive of infants consuming enriched whole-grain infant cereals with a high predictive value of about 93%.

A Brief Overview of Lab - Scale Apparatuses Used in the Recent Years for Experimental Investigations on Gas Hydrates

Gas hydrates are nonstoichiometric solid crystalline compound, whose formation is function of several parameters, such as pressure, temperature, fluid phase composition, reservoir saturation degree and others. One of the most critical aspects related to the research on this manner stays in differences existing between experimental results reached by using different experimental apparatuses. Moreover, laboratory scale reactors often have very contained dimensions with a consequent increasing influence of the boundary conditions. In the present paper, a brief overview of reactors used worldwide for experimental research on gas hydrates formation, is provided. In particular, the surface/volume ratio was calculated for each different typology of reactor and then associated with the ratio between moles of guest compound entrapped into water cages and moles injected. Even if such ratio does not represent the process efficiency, it is proportional to it. Consequently, that comparison was useful to well define the supporting effect of a greater S/V ratio on the hydrate formation process efficiency.

Caged Dexamethasone/Quercetin Nanoparticles, Formed of the Morphogenetic Active Inorganic Polyphosphate, are Strong Inducers of MUC5AC

Inorganic polyphosphate (polyP) is a widely distributed polymer found from bacteria to animals, including marine species. This polymer exhibits morphogenetic as well as antiviral activity and releases metabolic energy after enzymatic hydrolysis also in human cells. In the pathogenesis of the coronavirus disease 2019 (COVID-19), the platelets are at the frontline of this syndrome. Platelets release a set of molecules, among them polyP. In addition, the production of airway mucus, the first line of body defense, is impaired in those patients. Therefore, in this study, amorphous nanoparticles of the magnesium salt of polyP (Mg-polyP-NP), matching the size of the coronavirus SARS-CoV-2, were prepared and loaded with the secondary plant metabolite quercetin or with dexamethasone to study their effects on the respiratory epithelium using human alveolar basal epithelial A549 cells as a model. The results revealed that both compounds embedded into the polyP nanoparticles significantly increased the steady-state-expression of the MUC5AC gene. This mucin species is the major mucus glycoprotein present in the secreted gel-forming mucus. The level of gene expression caused by quercetin or with dexamethasone, if caged into polyP NP, is significantly higher compared to the individual drugs alone. Both quercetin and dexamethasone did not impair the growth-supporting effect of polyP on A549 cells even at concentrations of quercetin which are cytotoxic for the cells. A possible mechanism of the effects of the two drugs together with polyP on mucin expression is proposed based on the scavenging of free oxygen species and the generation of ADP/ATP from the polyP, which is needed for the organization of the protective mucin-based mucus layer.

Supporting effects of a N-doped carbon film electrode on an electrodeposited Ni@Ni(OH)2 core–shell nanocatalyst in accelerating electrocatalytic oxidation of oligosaccharides

The supporting effect of a N-doped carbon film induced superior crystallinity in electrodeposited Ni@Ni(OH)2 core–shell nanoparticles.