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Collapsible loess in Northwestern China challenges infrastructure backfilling. This study creates a new loess - based cement composite slurry (LCCS) with 8% cement and additives. LCCS has a high 180 - mm slump, a low permeability of 2.1 × 10⁻⁶ cm/s at 8% cement, and its collapsibility coefficient is less than 0.009. Durability tests show it has 27% better frost resistance than plain cement slurry, though with more sulfate - induced mass loss. LCCS uses 30% less cement than conventional CLSM, cutting costs and carbon emissions. Thus, it’s a promising green alternative for backfilling in such areas.

Nattokinase activity (NK), biogenic amine content and sensory properties of natto are of great significance to consumers, which are affected by strains and fermentation methods. In this study, changes in the pH, biogenic amine and free amino nitrogen (FAN) contents, NK and protease activities, and sensory characteristics of natto prepared using Bacillus subtilis GUTU09 combined with different strains (Lactobacillus, Bifidobacterium and Mucor) and fermentation methods were investigated. The combination of two strains showed the best fermentation performance among all samples. The NK and protease activity and FAN content in double-strain fermentation increased by 10.33 FU/g, 88.78 U/g, and 2.34 g/kg, respectively, compared with those in single-strain fermentation. Sensory evaluation demonstrated that mixed fermentation primarily affected the sensory acceptance. This method also reduced the contents of various biogenic amines in natto compared with single-strain fermentation. Tyramine, cadaverine, spermine, and spermidine were significantly reduced, whereas histamine was slightly increased. The total biogenic amines decreased from 390.76 mg/kg to a minimum of 16.16 mg/kg. Some Mucor strains also reduced the contents of various biogenic amines. In the dual-bacteria fermentation of Mucor and GUTU09, co-fermentation has advantages over stage-fermentation, with higher NK and protease activity and higher sensory scores. Correlation analysis showed that the formation and accumulation of some biogenic amines in natto prepared using different microbial combinations were related to NK activity and pH. All these results showed that the quality of natto was improved by mixed fermentation and suitable fermentation methods, which laid a foundation for its potential industrial application.

To enhance the construction foundation safety in the loess regions of Northwest China, this study systematically investigated the collapsibility characteristics of loess from a construction site in Lanzhou through laboratory collapse tests under constant pressure. Regression modeling was employed to quantitatively evaluate the influence of key geotechnical parameters—including natural density, dry density, moisture content, void ratio, and compression modulus—on the collapsibility coefficient. Significant relationships were established between the collapsibility coefficient and void ratio, natural moisture content, and compression modulus. Furthermore, the standard method was used to determine the variation of potential collapse around piles with depth, revealing an exponential distribution trend. It is worth emphasizing that this study successfully developed an exponential function model based on easily obtainable parameters (natural density, dry density, moisture content, and compression modulus) for quantitatively predicting the collapsibility coefficient. In contrast to existing models, which often rely on single indicators and lack a multi-parameter collaborative evaluation system—resulting in limited engineering applicability—this study integrated five parameters to construct a comprehensive prediction model, filling the gap in multi-index evaluation systems. This model provides a practical tool for more accurately predicting loess collapse settlement and can be directly applied to risk assessment and mitigation design for building foundations and pile-soil interactions in similar loess environments in Northwest China.

Aiming at the problems of easy settlement and insufficient durability of traditional materials under special backfilling conditions in the northwest loess area, this study prepared controllable low-strength ready-mixed flow solidified soil (CLSM) with solid waste and alkali activator (NaOH and water glass). Through multi-dimensional test and mechanism analysis, the collaborative optimization of material performance and economy was realized, and the durability mechanism of extreme environment was revealed. In this study, the original loess in Lanzhou was used as the matrix, and the L 16 (4 5 ) orthogonal test design was used to construct the ‘28d compressive strength-cost’ double-objective optimization model combined with the entropy weight method. The influence weights of coal gangue, carbide slag, blast furnace slag and alkali activator were quantified, and the optimal mix ratio was determined to be 15% of coal gangue, 3% of carbide slag, 15% of blast furnace slag and 60% of alkali activator. Under this ratio, the 28d compressive strength of CLSM reached 4.44 MPa, and the cost was controlled at 73.23 yuan/ton, taking into account both mechanical properties and economy. The extreme environmental durability test shows that compared with the traditional cement soil, the mass loss rate of the optimal ratio CLSM decreases by 44.83% and the strength increases by 34.89% after 25 freeze–thaw cycles. After 25 times of sulfate dry–wet cycles, the mass loss rate decreased by 55.56%, and the strength increased by 40.01%, especially the resistance to dry–wet cycles was better. The micro-mechanism study revealed that the formation of CLSM strength experienced five stages: ‘alkali-activated depolymerization-three-dimensional network construction exchange agglomeration-secondary hydration enhancement-structural densification’ and High content of solid waste and alkali activator synergistically promoted the formation of C–S–H gel and ettringite. The order of porosity inhibition effect was alkali activator > blast furnace slag > coal gangue > carbide slag, and it was significantly negatively correlated with macroscopic properties. Engineering application verification shows that CLSM has good fluidity in site pouring. Although there are adverse effects in the pouring process, it provides a new material paradigm for green backfilling in the cold and arid regions of Northwest China. In this study, “waste treatment by waste” is realized through the synergistic excitation of solid waste. The multi-objective optimization method improves the scientificity of the ratio. The systematic revelation of extreme environmental durability and micro-mechanism provides theoretical support for the engineering application of fluid solidified soil, which has both environmental protection value and engineering guiding significance.

The bottom uplift pile, which has been applied in practical projects, has the following advantages: the pile body is not easy to crack, good bearing characteristics, and small displacement of the pile top. Based on the bearing capacity test of foundation piles in the third stage expansion project of Lanzhou Zhongchuan International Airport, the upper part pile of the self-balancing test method was used to simulate the bottom uplift pile, and the anchor piles in the anchor pile method were regarded as normal uplift piles. The bearing characteristics of the bottom uplift pile in a layered foundation were studied by comparing these two kinds of piles. The results show that under the same displacement of the pile top, the ultimate uplift bearing capacity of the bottom uplift pile can be more than twice that of the normal uplift pile because of the fully exerted frictional resistance of the soil at the bottom of the pile, the Poisson effect of the pile body and the avoidance of the influence of pile body deformation on the pile top displacement. The maximum axial force of the bottom uplift pile appears at the bottom of the pile and gradually decreases from the bottom to the top, which is opposite to that of the normal uplift pile. The properties and thickness of the soil layers around the pile have a great influence on the distribution curves of the frictional resistance along the pile length of the two kinds of uplift piles. With changing soil layer conditions, the distribution curve may be a \"parabola\", a \"straight line\" or a \"double line\". The soil property plays a decisive role in the frictional resistance, which may cause softening. The influence of the pile diameter on the ultimate uplift bearing capacity is greater than that of the pile length, while the elastic modulus of the pile has little influence.

Lactobacilli have been widely concerned for decades. Bacteria of the genus Lactobacillus have been commonly employed in fermented food to improve the appearance, smell, and taste of food or prolong its shelf-life. They comprise 261 species (by March 2020) that are highly diverse at the phenotypic, ecological, and genotypic levels. Some Lactobacilli strains have been documented to be essential probiotics, which are defined as a group of living microorganisms that are beneficial to the health of the host when ingested in sufficiency. However, the characterization, high-density fermentation, and the production of a directed vat set (DVS) starter of Lactobacilli strains used in the food industry have not been systematically reported. This paper mainly focuses on reviewing Lactobacilli as functional starter cultures in the food industry, including different molecular techniques for identification at the species and strain levels, methods for evaluating Lactobacilli properties, enhancing their performance and improving the cell density of Lactobacilli, and the production techniques of DVS starter of Lactobacilli strains. Moreover, this review further discussed the existing problems and future development prospects of Lactobacilli in the food industry. The viability and stability of Lactobacilli in the food industry and gastrointestinal environment are critical challenges at the industrial scale. The new production equipment and technology of DVS starter of Lactobacilli strains will have the potential for large-scale application, for example, developing low-temperature spray drying, freezing granulation drying, and spray freeze-drying.

Natto is a popular food because it contains a variety of active compounds, including nattokinase. Previously, we discovered that fermenting natto with the combination of Bacillus subtilis GUTU09 and Bifidobacterium animalis subsp. lactis BZ25 resulted in a dramatically better sensory and functional quality of natto. The current study further explored the effects of different fermentation parameters on the quality of natto fermented with Bacillus subtilis GUTU09 and Bifidobacterium BZ25, using Plackett–Burman design and response surface methodology. Fermentation temperature, time, and inoculation amount significantly affected the sensory and functional qualities of natto fermented with mixed bacteria. The optimal conditions were obtained as follows: soybean 50 g/250 mL, triangle container, 1% sucrose, Bacillus subtilis GUTU09 to Bifidobacterium BZ25 ratio of 1:1, inoculation 7%, fermentation temperature 35.5 °C, and fermentation time 24 h. Under these conditions, nattokinase activity, free amino nitrogen content, and sensory score were increased compared to those before optimization. They were 144.83 ± 2.66 FU/g, 7.02 ± 0.69 mg/Kg and 82.43 ± 5.40, respectively. The plate thrombolytic area and nattokinase activity both increased significantly as fermentation time was increased, indicating that the natto exhibited strong thrombolytic action. Hence, mixed-bacteria fermentation improves the taste, flavor, nattokinase activity, and thrombolysis of natto. This research set the groundwork for the ultimate manufacturing of natto with high nattokinase activity and free amino nitrogen content, as well as good sensory and thrombolytic properties.

In the present work, the optimization of extraction, emulsifying properties, and biological activities of polysaccharides from Lentinula edodes Sing (LES) were studied. The results showed LES polysaccharides extracted by hot water or ultrasonication are a group of β-glucan. Among all the samples, the one extracted by hot water showed the best emulsifying capacity. In addition, the results demonstrated that LES polysaccharide had strong scavenging activities in vitro on DPPH and ABTS radicals, which reached the highest level for the one extracted by 90 min ultrasonication (p < 0.05). Overall, Lentinula edodes Sing polysaccharides (LESPs) may have potential applications as emulsifying agents in food industries.

Sn-1,3 extracellular Aspergillus niger GZUF36 lipase (EXANL1) has wide application potential in the food industry. However, the A. niger strain has defects such as easy degradation and instability in the expression of sn-1,3 lipase. To obtain a stable expression of this lipase and its subsequent enzymatic properties, the gene encoding EXANL1 was cloned and expressed in Escherichia coli BL21 (DE3) cells using pET-28a as the expression vector. The temperature-induced conditions were optimized, and we successfully achieved its active expression in E. coli. These conditions significantly influenced the active expression of EXANL1 (P < 0.05), and the highest enzyme activity of the supernatant of lysis cells expressed at 20 °C was at 7.02 ± 0.05 U/mL. The expressed recombinant EXANL1 was purified using Ni–NTA, showing an estimated relative molecular mass of 35 kDa. The recombinant EXANL1 exhibited maximum activity at 35 °C and pH 4.0, with a wide acid pH range. Thin-layer chromatography analysis showed that the enzyme displayed sn-1,3 positional selectivity toward triolein. The recombinant EXANL1 could maintain its relative activities (> 80%) after 24 h of incubation at pH 3–10, suggesting its suitability for a wide range of industrial applications. After comparing these properties with those of the other A. niger lipases, we found that some key amino acids may play a decisive role in enzymology. This work laid a foundation for the stable expression of the EXANL1 gene and its potential industrial application.

Natto is a high-value fermented soybean produced by B. subtilis. However, B. subtilis produces a pungent amine odor. This study compared the volatile organic compounds (VOCs), free amino acids (FAAs) and biogenic amines (BAs), nattokinase (NK) of natto made by two-strain fermentation with Bifidobacterium animalis BZ25 and Bacillus subtilis GUTU09 (NMBB) and that of natto made by single-strain fermentation with Bacillus subtilis GUTU09 (NMB). Compared with NMB, volatile amine substances disappeared, ketones and aldehydes of NMBB were reduced, and alcohols increased. Besides that, the taste activity value of other bitter amino acids was lowered, and BA content was decreased from 255.88 mg/kg to 238.35 mg/kg but increased NK activity from 143.89 FU/g to 151.05 FU/g. Correlation analysis showed that the addition of BZ25 reduced the correlation between GUTU09 and BAs from 0.878 to 0.808, and pH was changed from a positive correlation to a negative one. All these results showed that the quality of natto was improved by two-strain co-fermentation, which laid a foundation for its potential industrial application.