Search

ABSTRACT: Traditional fermented milks are produced through an inoculation process that involves the deliberate introduction of microorganisms that have been adapted and perpetuated across successive generations. However, the changes in the microbiota of traditional fermented milk during long-term inoculation fermentation in a laboratory environment remain unclear. In this study, we collected 5 samples of traditional fermented milk samples from 5 different counties in Tibet (3 kurut products) and Xinjiang (2 tarag products) of China, which served as starter cultures for a 9-mo continuous inoculation fermentation experiment. We analyzed the inter- and intrapopulation variations in the microbial communities of the collected samples, representing their macrodiversity and microdiversity, using shotgun metagenomic sequencing. Across all samples, we obtained a total of 186 high-quality metagenomic-assembled genomes, including 7 genera and 13 species with a relative abundance of more than 1%. The majority of these genomes were annotated as Lactobacillus helveticus (60.46%), Enterococcus durans (9.52%), and Limosilactobacillus fermentum (6.23%). We observed significant differences in species composition and abundance among the 5 initial inoculants. During the long-term inoculation fermentation, we found an overall increasing trend in species diversity, composition, and abundances of carbohydrate metabolism module-encoding genes in the fermented milk bacterial metagenome, while the fermented milk virome exhibited a relatively narrow range of variation. Lactobacillus helveticus, a dominant species in traditional fermented milk, displayed high stability during the long-term inoculation fermentation. Our study provides valuable insights for the industrial production of traditional fermented milk.

Alcoholic liver disease is one of the main causes of global liver disease-related deaths, which has emerged as a major health concern for people. In this study, a peptide was prepared from Pinctada Martensii meat (named HPM-3), and its protective effect against alcohol-induced liver damage in mice was investigated. The results indicated that intervention of HPM-3 significantly decreased the levels of transaminase and lactate dehydrogenase in serum, and improved the antioxidant enzyme activities in the liver. Besides, HPM-3 could alleviate alcohol-induced liver injury by mediating Keap1/Nrf2 signaling pathway. Moreover, HPM-3 could preserve the diversity of the gut microbiota, and restore the relative abundance of some microbial communities that were impacted by alcohol intervention. HPM-3 intervention also affected the secretion of L-glutamine and other associated metabolites and mediated the related metabolic pathways. The results would help to clarify the mechanisms of protective effects of marine peptides against alcohol-induced liver injury.

Abstract Background Our previous study found that crude polysaccharide extracted from Sargassum fusiforme (PSF) exhibited excellent anti-photoaging activity, but the composition responsible for this activity remained unknown. Results In this study, three fractions (P1, P2 and P3) obtained by hot water extraction and column chromatographic separation from PSF were structurally characterized. The anti-photoaging activities of these isolated polysaccharides were evaluated using HaCaT cells. The results showed that P1, P2 and P3 were acidic polysaccharides with 42.94%, 40.75% and 2.21% uronic acid. In addition, the contents of sulfate groups were 3.01%, 10.05% and 7.44%, respectively. Moreover, their content of reducing sugar was low, and none of the fractions had a triple-stranded helical structure. P1 had the largest average molecular weight of 208.89 kDa, while P2 and P3 had a relatively lower molecular weight of 154.09 and 151.71 kDa, respectively. Treatment with P2 effectively safeguarded the viability of HaCaT cells exposed to UVB irradiation. Additionally, it inhibited the secretion of MMP-1 and MMP-3 while elevating the content of hydroxyproline (HYP) in the cell supernatant. Methylation and NMR analysis suggested the main structure of P2 might be → [4)-β-ManA-(1]23 → 4)-β-ManA-(1 → 3)-β-d-Glcp-(1 → 4)-β-d-Glcp-(1 → 4)-β-d-Glcp-(1 → . The two terminal groups of β-ManA-(1 → and β-d-Glcp-(1 → were connected via the glycosidic bonds of → 3, 4)-O-3 in β-ManA-(1 → and O-6 in → 4, 6)-β-d-Glcp-(1 → , respectively. Conclusions These findings will open new avenues for exploring the potential use of Sargassum fusiforme polysaccharide, particularly P2, as a functional ingredient with anti-photoaging activity. Graphical Abstract

Abstract Although ultraviolet (UV)/H2O2 treatment could effectively improve the bioactivities of polysaccharides, the relationship between free radical‐induced structural changes and the bioactivities of products remains unknown. Therefore, this work investigated the changes in the chemical characteristics and chain conformations of degraded dextrans by the UV/H2O2 system as well as their antioxidant and anti‐inflammatory activities. The apparent degradation efficiencies of dextrans under different UV/H2O2 parameters were first investigated. UV/H2O2 treatment effectively destroyed the pyranose rings and glycosidic bonds of dextrans and significantly improved their uronic acid and carboxy contents. Furthermore, conformational studies revealed that besides the rapid decrease in the molecular weight, the compact spherical conformation of dextrans was gradually depolymerized into the flexible random coil conformation. Moreover, the significant antioxidant and anti‐inflammatory activities of the degraded dextrans were mainly attributed to their more extended random coil chains, increased quantity of reducing groups, and lower molecular sizes. This study contributes to investigating the structure–activity relationship of polysaccharides prepared by free radicals‐mediated degradation.

Abstract The intestinal barrier is critical in maintaining gut homeostasis and host health. The intestinal barrier dysfunction contributes to intestinal and systemic diseases like inflammatory bowel disease, colorectal cancer, and metabolic syndromes. This review summarizes the physicochemical properties of three main kinds of brown seaweed polysaccharides (BSP), laminarin, fucoidan, and alginate, along with their absorption and metabolism in the intestine and their effects on the intestinal barrier. The physicochemical properties of BSP were closely related to their beneficial effects on intestinal health. BSP were not digested directly in the upper gastrointestinal tract but could be utilized through fermentation by the gut microbiota. BSP kept the integrity of intestinal epithelium by ameliorating intestinal oxidative stress through the nuclear factor erythroid 2‐related factor 2 signaling pathway. They also reduced tight junction dysfunction and intestinal permeability and increased the expression of mucins. Moreover, BSP regulated the composition and abundance of gut microbiota and promoted the production of beneficial metabolites such as short‐chain fatty acids. This review will help to understand the gut health‐promoting functions of the natural compounds derived from brown seaweed and offer a new perspective on intestinal disease prevention and therapy with high effectiveness and safety.

Through the stimulation method of large-scale hydraulic fracturing, the spontaneous imbibition capacity of the water phase in the shale reservoir has great influence on the effect of stimulation. Generally, the lacustrine shale has the characteristics of high clay minerals content, strong expansibility, development of nanopores and micro-pores, and underdevelopment of fractures, which leads to the unclear behavior of spontaneous imbibition of aqueous phase. The lacustrine shale of Da'anzhai Member and marine shale of Longmaxi Formation in Sichuan Basin were selected to prepare both the shale matrix sample and fractured shale sample, and the spontaneous imbibition experiment of simulated formation water was carried out. By means of an XRD test, SEM observation, nuclear magnetic resonance test and linear expansion rate test, the mineral composition, the structure of pores and fractures, the capacity of hydration and expansion of both lacustrine and marine shale are compared and analyzed. The results show that the average spontaneous imbibition rate of lacustrine shale is 60.8% higher than that of marine shale within the initial 12 hours of imbibition. The lacustrine shale has faster imbibition rate than the marine shale in the initial stage of spontaneous imbibition. However, the lacustrine shale has underdeveloped pores and fractures, as well as poor connectivity of pores. Besides, the strong hydration and expansion of clay minerals can easily lead to dispersion and migration of clay minerals on the fracture surface, which will plug up the seepage channels, resulting in poor capacity of spontaneous imbibition. The spontaneous imbibition rate in the middle and late stage of Lacustrine shale is obviously lower than that of the marine shale. The overall spontaneous imbibition rate ability of the lacustrine shale is less than that of the marine shale. According to the characteristics of water imbibition of lacustrine shale, considering the dual effects of hydration expansion of clay minerals on the effective reconstructed volume, the microfractures can be initiated and extended by fully utilizing the hydration of shale. Acidification treatment, oxidation treatment or high temperature treatment can be used to expand pore space, enhance water phase imbibition capacity and improve multi-scale mass transfer capacity of the lacustrine shale.

Polysaccharides derived from diverse sources exhibit distinct rheological and gel properties, exerting a profound impact on their applicability in the food industry. In this study, we collected five Gracilaria chouae samples from distinct geographical regions, namely Rizhao (RZ), Lianyungang (LYG), Ningde (ND), Beihai (BH), and a wild source from Beihai (BHW). We conducted analyses on the chemical composition, viscosity, and rheological properties, as well as gel properties, to investigate the influence of chemical composition on variations in gel properties. The results revealed that the total sugar, sulfate content, and monosaccharide composition of G. chouae polysaccharides exhibit similarity; however, their anhydrogalactose content varies within a range of 15.31% to 18.98%. The molecular weight distribution of G. chouae polysaccharides ranged from 1.85 to 2.09 × 103 kDa. The apparent viscosity of the LYG and BHW polysaccharides was relatively high, whereas that of RZ and ND was comparatively low. The gel strength displayed a similar trend. BHW and LYG exhibited solid-like behavior, while ND, RZ, and BH demonstrated liquid-like characteristics at low frequencies. The redundancy analysis (RDA) analysis revealed a positive correlation between the texture profile analysis (TPA) characteristics and anhydrogalactose. The study could provide recommendations for the diverse applications of G. chouae polysaccharides derived from different geographical regions.

Abstract An alginate (named P1) prepared from Sargassum fusiforme has been proven to have significant anti‐photoaging activity in our previous study. In this study, alginate lyase was used to obtain P1 hydrolysates with different molecular weights, and their structural characteristics and anti‐photoaging activity were compared. Results showed that alginate lyases could rapidly degrade the molecular weight of P1 and slightly changed its chemical composition. Fourier transform infrared spectra indicated that alginate lyase treatment did not change the main functional groups of P1. Moreover, the inhibitory effects of P1 on MMPs (MMP‐1, MMP‐3 and MMP‐9) and reactive oxygen species were also improved after hydrolyzed with alginate lyase, especially sample A‐30 (hydrolysis for 30 min). Methylation and nuclear magnetic resonance results indicated that the main chain of A‐30 was →4)‐β‐ManA‐(1→4)‐α‐GulA‐(1→4)‐β‐ManA‐(1→4)‐β‐ManA‐(1→4)‐α‐GulA‐(1→4)‐β‐ManA‐(1→3, 4)‐β‐ManA‐(1→, with the end group of α‐Fucp‐(1→ attached to the O‐3 position of →3, 4)‐β‐ManA‐(1→ on the side chain. It indicated that alginate lyase did not change the backbone of P1 but decreased the molecular or degree of polymerization at 30 min of hydrolysis. This is the first report on the anti‐photoaging activity of alginate hydrolysates. The results will provide effective theoretical support for improving the utilization and promoting the application of S. fusiforme.

Abstract People have become increasingly concerned about skin beauty and health issues, especially skin photoaging. Previous studies showed that skin photoaging was characterized by skin roughness and dryness. It was caused by UV radiation‐related dysregulation of matrix metalloproteinases (MMPs) and oxidative stress. Therefore, to investigate the antiphotoaging activity of polysaccharides, it is critical to establish the skin photoaging model, including the in vitro cellular model and the in vivo animal model. The in vitro cellular model is judged by cell viability, the MMPs expression, oxidative detection, and the quantities of inflammation cytokines. Moreover, both the damage to the epidermis and dermis of nude mice and the change of collagen content in the skin are indicators of the in vivo animal model. Thus, in this guideline, we tried to summarize the practice of antiphotoaging activity for polysaccharides.

The applications of fucoidan in the food industry were limited due to its high molecular weight and low solubility. Moderate degradation was required to depolymerize fucoidan. A few studies have reported that fucoidan has potential antibacterial activity, but its antibacterial mechanism needs further investigation. In this study, the degraded fucoidans were obtained after ultraviolet/hydrogen peroxide treatment (UV/H2O2) at different times. Their physicochemical properties and antibacterial activities against Staphylococcus aureus and Escherichia coli were investigated. The results showed that the average molecular weights of degraded fucoidans were significantly decreased (up to 22.04 times). They were mainly composed of fucose, galactose, and some glucuronic acid. Fucoidan degraded for 90 min (DFuc-90) showed the strongest antibacterial activities against Staphylococcus aureus and Escherichia coli, with inhibition zones of 27.70 + 0.84 mm and 9.25 + 0.61 mm, respectively. The minimum inhibitory concentrations (MIC) were 8 mg/mL and 4 mg/mL, respectively. DFuc-90 could inhibit the bacteria by damaging the cell wall, accumulating intracellular reactive oxygen species, reducing adenosine triphosphate synthesis, and inhibiting bacterial metabolic activity. Therefore, UV/H2O2 treatment could effectively degrade fucoidan and enhance its antibacterial activity.

Three Laminaria japonica polysaccharides (LJPs) extracted via water extraction (LJP-W), acid extraction (LJP-A), and enzymatic extraction (LJP-E) were used as raw materials to be cross-linked with chitosan and polyvinyl alcohol to prepare hydrogels. Compared with conventional hydrogel systems, all three types of LJP-based polysaccharide hydrogels exhibited better swelling properties (14 times their original weight) and the absorption ability of simulated body fluid (first 2 h: 6–10%). They also demonstrated better rigidity and mechanical strength. Young’s modulus of LJP-E was 4 times that of the blank. In terms of hemostatic properties, all three polysaccharide hydrogels did not show significant cytotoxic and hemolytic properties. The enzyme- and acid-extracted hydrogels (LJP-Gel-A and LJP-Gel-E) demonstrated better whole-blood coagulant ability compared with the water-extracted hydrogel (LJP-Gel-W), as evidenced by the whole blood coagulation index being half that of LJP-Gel-W. Additionally, the lactate dehydrogenase viabilities of LJP-Gel-A and LJP-Gel-E were significantly higher, at about four and three times those of water extraction, respectively. The above results suggested that LJP-Gel-A and LJP-Gel-E exhibited better blood coagulation capabilities than LJP-Gel-W, due to their enhanced platelet enrichment and adhesion properties. Consequently, these hydrogels are more conducive to promoting coagulation and have good potential for wound hemostasis.

Tight oil reservoir is usually characterized by poor physical properties with oil recovery less than 10%. The objective of the study is to investigate the effect of 4 different types of surfactants to change rock surface tension and interfacial tension as well as its impact on enhanced oil recovery (EOR) in tight oil reservoirs. Results shows that the fluoride FC-1 and GS surfactant has more potential for wettability alteration and interfacial tension reduction respectively. The interfacial tension decreased from 6.072 mN/m to 2.04 mN/m, 0.03 mN/m, 0.1 mN/m, and 0.04 mN/m under the action of FC-1, GS surfactant, FC-2, and FC-3, respectively. FC-1 made the wettability changed from original hydrophilic or oil-hydrophilic to hydrophobic and oil-phobic. While the effect of wettability modification by other three was not so obvious and the contact angle was no more than 45 degrees. So, the GS and FC-1 was selected for displacement tests to investigate the effect in augmenting injection and enhancing oil recovery. The average reduction rate of injection pressure by fluoride and Gemini surfactant was 32.4% and 14.2%, respectively. Under the action of fluoride and GS surfactant, the water-phase permeability increased by 36.8% and 29.9%, respectively. The improvement of recovery mainly occurred in primary water flooding, while the amount of oil displaced by surfactant solution and secondary water flooding was little or even no, with the recovery efficiency improved by 0–8.4%. The effect of fluoride was more obvious, revealing that changing rock wettability is more favorable than reducing the interfacial tension for oil recovery in tight sandstone oil reservoirs.

Improving silage production by adding exogenous microorganisms not only maximizes nutrient preservation, but also extends product shelf life. Herein, changes in the quality and quantity of Lactobacillus plantarum PS-8 (PS-8) -inoculated alfalfa (Medicago sativa) during silage fermentation were monitored at d 0, 7, 14, and 28 (inoculum dose of PS-8 was 1 × 105 colony forming units [cfu]/g fresh weight; 50 kg per bag; 10 bags for each time point) by reconstructing metagenomic-assembled genomes (MAG) and Growth Rate InDex (GRiD). Our results showed that the exogenous starter bacterium, PS-8 inoculation, became the most dominating strain by d 7, and possibly played a highly active role throughout the fermentation process. The pH value of the silage decreased greatly, accompanied by the growth of acid-producing microorganisms namely PS-8, which inhibited the growth of harmful microorganisms like molds (4.18 vs. 1.42 log cfu/g) and coliforms (4.95 vs. 0.66 log most probable number [MPN]/g). The content of neutral detergent fiber (NDF) decreased significantly (41.6% vs. 37.6%; dry matter basis). In addition, the abundance and diversity of genes coding microbial carbohydrate-active enzymes (CAZymes) increased significantly and desirably throughout the fermentation, particularly the genes responsible for degrading starch, arabino-xylan, and cellulose. Overall, our results showed that PS-8 was replicating rapidly and consistently during early- and mid-fermentation phases, promoting the growth of beneficial lactic acid bacteria and inhibiting undesirable microbes, ultimately improving the quality of silage.

Abstract The search for novel efficient antibacterial agents is attracting a great attention due to the unregulated use of common antibiotics and development of multidrug‐resistant bacteria strains. This paper proposes an eco‐friendly approach to obtain stable chitosan‐capped silver nanoparticles with controlled physicochemical and biological properties using reducing and stabilizing capacity of chitosan. The study of the influence of chitosan characteristics on the kinetic of Ag+ reduction showed that an increase in polysaccharide molecular weight led to a decrease in their reducing ability. The synthesized silver nanoparticles were characterized by UV and FTIR spectroscopy, TEM, XRD, DLS. The relationships between physicochemical characteristics of the formed silver nanoparticles and the type of used chitosan, as well as synthesis temperature, were determined. It has been demonstrated that spherically‐shaped (13–27 nm) and positively‐charged (zeta‐potential 26.1–29.5 mV) silver nanoparticles with a single symmetric SPR band at 408–418 nm are stable during 6 months in a colloidal form, and can be produced with the assistance of low‐molecular weight chitosan (20–30 kDa) at 95°C. The synthesized silver nanoparticles enhanced the antibacterial activity of kanamycin and ampicillin against both gram‐negative and gram‐positive bacteria. These results revealed the prospects for the application of chitosan‐capped silver nanoparticles to create new effective antibacterial systems (gels, films, etc).

The main purpose of this study was to analyze the structural properties and anti-inflammatory activity of the purified fractions derived from UV/H2O2-degraded polysaccharides from Sargassum fusiforme. Results indicated that twofractions with different monosaccharide compositions and morphological characteristics, PT-0.25 (yield 39.5%) and PT-0.5 (yield 23.9%), were obtained. The average molecular weights of PT-0.25 and PT-0.5 were 14.52 kDa and 22.89 kDa, respectively. In addition, PT-0.5 exhibited better anti-inflammatory activity with a clear dose dependence. The mechanism was associated with the inhibition of LPS-activated Toll-like receptor 4-mediated inflammatory pathways in RAW264.7 cells. The results showed that PT-0.5 was a complex polysaccharide mainly composed of 4-Fucp, t-Manp, 6-Galp, t-Fucp, and 3,4-GlcAp. These results would provide theoretical support for studying the structural properties and biological activities of UV/H2O2-degraded polysaccharides.

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease nowadays. Currently, there is no officially approved drug to treat NAFLD. In view of the increasing global prevalence of NAFLD and an absence of treatments, the development of effective treatments is of utmost importance. β-glucan, a natural bioactive polysaccharide, has demonstrated hepatoprotective effects in NAFLD prevention and treatment. This review solely focuses on gathering the published preclinical animal studies that demonstrated the anti-liver injury, anti-steatotic, anti-inflammatory, anti-fibrotic, and antioxidant activities of β-glucan. The impact of β-glucan on gut microbiota and its metabolites including short-chain fatty acids and bile acids as the underlying mechanism for its bioactive beneficial effect on NAFLD is also explored. Given the limited knowledge of β-glucan on anti-fibrotic activity, bile acid metabolism, and gut microbiota function, additional relevant research is highly encouraged to lay a solid foundation for the use of food-derived β-glucan as a functional food for NAFLD. It is envisaged that further investigation of food-derived β-glucan in human clinical studies should be carried out for its wider utilization.

In this work, new chitosan derivatives (CS1-CS6) were obtained by short-term hydrothermal treatment. The formation of chitosan derivatives occurred through two simultaneous processes: hydrolysis and Maillard self-reaction. The synthesized chitosan-based Maillard self-reaction products were characterized by physical measurements and spectroscopic methods (viscometry, UV–Vis, FTIR, 1H NMR, TGA and XRD). The results showed that hydrothermal treatment of chitosan solutions leads to a significant decrease (from ∼ 66500 up to ∼ 20150 Da) in the viscosity-average molecular weight of polymer. It has been shown that the antiradical activity of CS1-CS6 was 2-5 times higher in comparison with the activity of unmodified chitosan (1.42 µg ascorbic acid equivalents/mg). The enhanced (R value ≥ 4-5) antimicrobial activity of CS1-CS5 derivatives against gram-negative and gram-positive bacteria including thermophilic highly heat-resistant Geobacillus stearothermophilus has been demonstrated.

A large number of microbial genomes have already been identified from the human gut microbiome, but the understanding of the role of the low-abundance species at the individual level remains challenging, largely due to the relatively shallow sequencing depth used in most studies. To improve genome assembling performance, a HiSeq-PacBio hybrid, ultra-deep metagenomic sequencing approach was used to reconstruct metagenomic-assembled genomes (MAGs) from 12 fecal samples. Such approach combined third-generation sequencing with ultra-deep second-generation sequencing to improve the sequencing coverage of the low-abundance subpopulation in the gut microbiome. Our study generated a total of 44 megabase-scale scaffolds, achieving four single-scaffolds of complete (circularized, no gaps) MAGs (CMAGs) that were the first circular genomes of their species. Moreover, 475 high-quality MAGs were assembled across all samples. Among them, 234 MAGs were currently uncultured, including 24 MAGs that were not found in any public genome database. Additionally, 287 and 77 MAGs were classified as low-abundance (0.1–1%) and extra-low-abundance (

The functional beverages (FBs) are an important segment of functional food products due to health benefits they provide and their appealing sensory characteristics, suitability and affordability. FBs market offers many opportunities for new product development (nutraceuticals, colorants, plant-based medicines and products) with desirable and effective composition of nutrients and bioactive molecules (BAMs) aimed to deliver health benefits and improve human well-being. Recently, the use of medicinal and aromatic plants (MAPs) in the production of FBs has become increasingly popular due to specific content of nutrients (amino and fatty acids) and BAMs (volatile and non-volatile) attributed to the biological effects and health benefits. BAMs are stored in leaves, flowers, fruits, seeds, barks and roots, and they mostly include phenolics (phenolic acids, flavonoids, tanins, anthocyanins, lignans and stilbenes), essential oils (EOs), terpenoids, alkaloids, phytosterols and saponins. The aromatic features of MAPs are mainly related to volatile compounds of EOs, but the presence of non-volatile compounds, such as phenolics, also contributes to the specific sensory properties. Phytochemical profiling of plant species containing specific and complex mixtures of BAMs, provides numerous opportunities for the development of new categories of FBs, but also opens new challenges in their isolation using conventional and advanced extraction techniques, as well as determination of potential biological effects. This review summarizes the categories of the most common FBs, BAMs from selected MAPs and their biological effects, extraction techniques suitable for production of plant extracts and EOs, product quality and prediction trends, and several directions towards future research on FBs development strategies.

The high molecular weight and poor solubility of seaweed polysaccharides have limited their function and application. In this study, ultraviolet/hydrogen peroxide (UV/H2O2) treatment was used to prepare low-molecular-weight seaweed polysaccharides from Sargassum fusiforme. The effects of UV/H2O2 treatment on the physicochemical properties and anti-photoaging activity of S. fusiforme polysaccharides were studied. UV/H2O2 treatment effectively degraded polysaccharides from S. fusiforme (DSFPs), reducing their molecular weight from 271 kDa to 26 kDa after 2 h treatment. The treatment did not affect the functional groups in DSFPs but changed their molar percentage of monosaccharide composition and morphology. The effects of the treatment on the anti-photoaging function of S. fusiforme polysaccharides were investigated using human epidermal HaCaT cells in vitro. DFSPs significantly improved the cell viability and hydroxyproline secretion of UVB-irradiated HaCaT cells. In particular, DSFP-45 obtained from UV/H2O2 treatment for 45 min showed the best anti-photoaging effect. Moreover, DSFP-45 significantly increased the content and expression of collagen I and decreased those of pro-inflammatory cytokines, including interleukin-1β, interleukin-6, and tumor necrosis factor-α. Thus, UV/H2O2 treatment could effectively improve the anti-photoaging activity of S. fusiforme polysaccharides. These results provide some insights for developing novel and efficient anti-photoaging drugs or functional foods from seaweed polysaccharides.

High-temperature thermal stimulation (HTS) can effectively remove the damage caused by water phase trapping during the drilling and completion of tight oil and hydraulic fracturing of gas reservoirs. Since HTS induces new rock fracture, the permeability of a reservoir will be increased to a certain extent. However, there are no standardized methodologies for pretreatment, experimental procedures, or evaluation indicators for HTS rock samples. Taking the Longmaxi Formation shale from the Sichuan Basin as the research object, an experimental process for evaluating the impact of HTS on permeability was established. The temperature increased at a rate of 5 °C/min, considering the conditions of dry and water-bearing rock samples. Three variables are included in the evaluation index for HTS of shale reservoirs: threshold temperature, raise multiples of permeability in 4 MPa confining pressure, and in-situ conditions. The results show that the threshold temperature of the dry shale is 650–700 °C, while the water-bearing shale has two threshold temperatures. Furthermore, the low temperature is 100–150 °C, while the high temperature is 450–500 °C. The permeability increase ratio of drying shale samples is 1.5–10.0 after HTS under in-situ effective stress, while that of water-bearing shale samples reach 20–50. This research has shown that using the HTS method to reduce water phase trapping damage and drastically improves well production are being conducted in a shale gas reservoir with horizontal wells and staged hydraulic fracturing. Our recommended experimental methods and evaluation indicators are effective in establishing the HTS potential of a shale reservoir.

The permeability jail refers to a specific water saturation range in a tight gas reservoir, where almost no gas or water phase can flow effectively. In the process of drilling and fracturing, water saturation rises and falls into the permeability jail. To reduce or avoid falling into the permeability jail in the recovery process, a method for measuring gas–water relative permeability of tight sandstone is established here that considers salt sensitivity, gas slippage effect, stress sensitivity, and high bound water saturation. Then, the permeability jail range was determined to provide guidance and suggestions for field application. Considering a typical tight sandstone as an example, the proposed method was used to expand the measurement range of gas–water relative permeability and observe the permeability jail range, laying an experimental foundation for accurately determining the permeability jail range in a given formation. The Byrnes model can preliminarily predict the permeability jail range with accurate bound water saturation and residual gas saturation. When the permeability jail phenomenon occurs in the core, the larger the permeability is, the smaller the permeability jail range will be; and the larger the porosity is, the smaller the permeability jail range will be. When the permeability jail phenomenon occurs in the tight sandstone reservoir, the damage to the reservoir due to external fluid and solid phased particles should be strictly controlled. The damage is stronger, the permeability and porosity decline, and the permeability jail range is wider. Other gases or solvents can be used as fracturing fluids to minimize formation damage.

In view of the existing Deepfake detection algorithms, such problems as low accuracy and poor interpretability are common.A neural network model combining the double attention was proposed, which used channel attention to capture the abnormal features of false faces and combined the location of spatial attention to focus the abnormal features.To fully learn the contextual semantic information of the abnormal part of the false face, so as to improve the effectiveness and accuracy of face changing detection.In addition, the decision-making area of real and fake faces was shown effectively in the form of thermal diagram, which provided a certain degree of explanation for the face exchange detection model.Experiments on FaceForensics ++ open source data set show that the detection accuracy of proposed method is superior to MesoInception, Capsule-Forensics and XceptionNet.

Oxidizing stimulation of organic-rich shale reservoirs, as a supplement of hydraulic fracturing, was proposed to enhance shale gas recovery. Previous publications revealed that the interaction between organic-rich shale and oxidative fluids causes the components’ dissolution, which induces lots of pores and microfractures, resulting in rock microfracturing without confined pressure and associated increments of the matrix permeability, and improving unpropped fracture conductivity. However, the enhancement of shale gas recovery with oxidative fluids still lacks an implementation clue targeted for specific engineering problems. In recent years, water–rock interaction inducing microfractures indicates a positive effect of retained fracturing fluid on the stimulation after the fracturing operation, which sheds light in the enhancement of shale gas production by shut-in. The objectives of this study are to provide a new perspective whereby the shut-in performance to enhance shale gas recovery could be increased by the injection of oxidative fluids into the formation during the fracturing operation. Firstly, the mechanisms of shut-in performance increased by oxidative dissolution, which illustrate the increment of the density of fracture networks, the improvement of fracture network conductivity, and the promotion of gas desorption and diffusivity, are demonstrated. Then, the feasibility of using oxidative fluids to increase shut-in performance, which follows the geological and engineering characteristics of organic-rich shale reservoirs, is evaluated. Finally, according to the analysis of production performance for two typical types of shale gas wells, in which one is a low gas production and a high fracturing fluid recovery (LGP-HFR) and the other is a high gas production and a low fracturing fluid recovery (HGP-LFR), a shut-in strategy with oxidative fluids to enhance shale gas recovery is developed. This indicates that the injection of oxidative fluids during the fracturing operation may become a promising and cost-effective approach to enhance shale gas recovery.

Whole grain is the primary food providing abundant dietary fibers (DFs) in the human diet. DFs from rice bran and wheat bran have been well documented in modulating gut microbiota. This review aims to summarize the physicochemical properties and digestive behaviors of DFs from rice bran and wheat bran and their effects on host gut microbiota. The physicochemical properties of DFs are closely related to their fermentability and digestive behaviors. DFs from rice bran and wheat bran modulate specific bacteria and promote SAFCs-producing bacteria to maintain host health. Moreover, their metabolites stimulate the production of mucus-associated bacteria to enhance the intestinal barrier and regulate the immune system. They also reduce the level of related inflammatory cytokines and regulate Tregs activation. Therefore, DFs from rice bran and wheat bran will serve as prebiotics, and diets rich in whole grain will be a biotherapeutic strategy for human health.

Focused on the lost circulation control in deep naturally fractured reservoirs, the multiscale structure of fracture plugging zone is proposed based on the theory of granular matter mechanics, and the structural failure pattern of plugging zone is developed to reveal the plugging zone failure mechanisms in deep, high temperature, high pressure, and high in-situ stress environment. Based on the fracture plugging zone strength model, key performance parameters are determined for the optimal selection of loss control material (LCM). Laboratory fracture plugging experiments with new LCM are carried out to evaluate the effect of the key performance parameters of LCM on fracture plugging quality. LCM selection strategy for fractured reservoirs is developed. The results show that the force chain formed by LCMs determines the pressure stabilization of macro-scale fracture plugging zone. Friction failure and shear failure are the two major failure patterns of fracture plugging zone. The strength of force chain depends on the performance of micro-scale LCM, and the LCM key performance parameters include particle size distribution, fiber aspect ratio, friction coefficient, compressive strength, soluble ability and high temperature resistance. Results of lab experiments and field test show that lost circulation control quality can be effectively improved with the optimal material selection based on the extracted key performance parameters of LCMs. Key words: deep layer, fractured reservoir, lost circulation, fracture plugging zone, multi-scale structure, strength and stability, loss control material

Abstract Treatment for tumors depends on host immune system. The antitumor and immunoregulatory activities of Ulva lactuca polysaccharide (ULP) were evaluated in H22 tumor‐bearing mice and cyclophosphamide‐induced immunosuppressed mice, respectively. The structural properties of ULP were identified through multi‐angle laser light scattering, high‐performance liquid chromatography, Fourier‐transformed infrared, and nuclear magnetic resonance. It was composed of α‐D‐Manp‐(1→, →2,4)‐β‐L‐Rhap‐(1→, β‐D‐GlcpA‐(1→, β‐GalpA‐(1→, →2,4)‐α‐D‐Glcp‐(1→, and →6)‐β‐D‐Galp‐(1→ with the molecular weight of 1.46 × 105 Da. Its antioxidant, anti‐inflammatory, and antitumor effects were determined. Liver and tumor tissues were collected for histopathological, immunohistochemical, and western blotting analysis. ULP showed the great tumor growth inhibition of 74.41% compared with cyclophosphamide, which has side effects on immune system. ULP enhanced the expression of p53 to inhibit tumorigenesis, promoted the activation of IKKα, and inhibited the activation of p65 within the NF‐κB pathway. ULP inhibited the tumor growth through downregulating the expressions of PI3K/Akt and mTOR, and promoting BAX/Bcl‐2 ratio. The inhibition of TRAF2/TNF‐α and CD31/VEGF achieved a direct killing effect on tumor cells and inhibited tumor proliferation by inhibiting angiogenesis, respectively. Moreover, ULP increased the levels of immunoglobulin M and total superoxide dismutase, decreased the level of methane dicarboxylic aldehyde, and inhibited the activation of PI3K/AKT/mTOR/p70S6k pathways. The results showed that ULP exhibited pronounced antitumor activity and immunoregulatory effect.

Abstract This paper presents an investigation into the effect of rock physical parameters on water phase trapping (WPT) damage in tight gas reservoirs. The investigation involved water imbibition and drainage experiments that were performed to simulate the WPT formation process. Gas permeability was measured before and after WPT, and an empirical formula was used to determine water film thickness in order to examine the influence of WPT on effective gas flow channel. Results showed that the average water saturation of 15 tight core samples increased from 19.41% to 44.76% during water imbibition and declined to 38.72% after drainage. Increments in water saturation caused a degree of damage to gas permeability in the 36.03%‐78.10% range with an average value of 59.31%. Comparative analysis showed that the dominant factors affecting WPT were average pore throat radius followed by rock permeability and porosity. Meanwhile, calculations showed that water film thickness in the 21.22‐38.18 nm range correlated to a reduced effective gas flow channel of 20.20‐45.15 nm caused by WPT, which suggests that tight rocks with smaller pore throats may be particularly sensitive to WPT damage. The relative size of the water film filling the pore throat, trapping gas, and reducing the effective gas flow channel together with the size of the pore throat itself were found to be the most common damage mechanisms of WPT and have proven to be fundamentally beneficial in understanding the controlling factors of these damage mechanisms.

Drainage coefficient has an important influence on the determination of the scale of drainage engineering and agricultural production. This paper calculated the drainage coefficient based on the calculation results of theoretical runoff using the empirical formula (QE) and the average draining method (QA), and discussed the drainage duration (TE) corresponding to the empirical formula and the area range (FA) corresponding to the average draining formula. The results showed that the observed runoff was less than the theoretical runoff. The design flow of the Wanyan River pumping station does not meet the drainage demand of the 5-year rainfall return period. For the 1-day rainfall with 3-year return period and 3-day rainfall, QE was higher than QA, and the design drainage duration was higher than TE, so it was safer to calculate the drainage coefficient using the empirical formula in the drainage engineering design. For 1-day rainfall greater than the 3-year return period, QA was higher than QE, and the design drainage duration was less than TE, and the results of the average draining formula were safer in the drainage engineering design. FA increased with the increase in rainfall duration and decreased with the increase in return period. When the rainfall duration and the drainage duration were long, the calculation results of the average draining formula were much smaller.

Pinctada martensii is a major marine pearl cultured species in southern China, and its meat is rich in protein, which is an excellent material for the preparation of bioactive peptides. In this study, the peptides from Pinctada martensii meat were prepared by simulated gastrointestinal hydrolysis, and after multistep purification, the structures of the peptides were identified, followed by the solid-phase synthesis of the potential antioxidant peptides. Finally, the antioxidant activities of the peptides were verified using HepG2 cells, whose oxidative stress was induced by hydrogen peroxide (H2O2). It was shown that the antioxidant peptide (S4) obtained from Pinctada martensii meat could significantly increase the cell viability of HepG2 cells. S4 could also scavenge reactive oxygen species (ROS) and reduce the lactate dehydrogenase (LDH) level. In addition, it could enhance the production of glutathione (GSH) and catalase (CAT) in HepG2 cells, as well as the expression of key genes in the Nrf2 signaling pathway. Three novel antioxidant peptides, arginine–leucine (RL), arginine–glycine–leucine (RGL), and proline–arginine (PR), were also identified. In conclusion, peptides from Pinctada martensii meat and three synthetic peptides (RGL, RL, PR) showed antioxidant activity and could have the potential to be used as antioxidant candidates in functional foods.

This study was aimed to characterize Gracilaria lemaneiformis polysaccharides and evaluate their protective effects on Lipopolysaccharide-induced injury in IEC-6 cells. The G. lemaneiformis polysaccharide was degraded by UV/H2O2 treatment and purified to three fractions named GLP-1.0 M, GLP-1.4 M and GLP-1.6 M. The purified fractions were mainly composed of galactose, glucose and xylose. The structural analysis showed that GLP-1.6 M was a typical sulfated red alga polysaccharide containing the linear backbone of β-(1 → 3)- and α-(1 → 4)-linked galactosyl residues, anhydro-galactose units. In the Lipopolysaccharide-induced IEC-6 cells model, GLP-1.6 M exerted the strongest in vitro anti-inflammatory activity by inhibiting the release and expressions of tumor necrosis factor-α, interleukin-6 and interleukin-1β by 89.93%, 67.82% and 38.06%, respectively. Meanwhile, GLP-1.6 M enhanced the intestinal barrier function via up-regulating the expressions of tight junctions and mucin. Therefore, the purified polysaccharide from G. lemaneiformis could be a promising candidate for maintaining intestinal health in the food and pharmaceutical industries.

Long-term exposure to ultraviolet-B (UVB) can cause photoaging. Peptides from Pinctada martensii meat have been shown to have anti-photoaging activities, but their mechanism of action is rarely studied. In this study, Pinctada martensii meat hydrolysates (PME) were prepared by digestive enzymes and then separated by ultrafiltration and Sephadex G-25 gel filtration chromatography to obtain a purified fraction (G2). The fraction G2 was identified by ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), and peptide sequences were synthesized by solid-phase synthesis. The mechanism of anti-photoaging activities was investigated using a human immortalised epidermal (HaCaT) cell model. Results showed that peptides from Pinctada martensii meat increased UVB-induced cell viability and reduced the contents of interstitial collagenase (MMP-1) and matrix lysing enzyme (MMP-3) in HaCaT cells. Furthermore, the fraction of G2 significantly downregulated the expression of p38, EKR, JNK, MMP-1, and MMP-3 in HaCaT cells. The peptide sequences Phe-His (FH), Ala-Leu (AL), Met-Tyr (MY), Ala-Gly-Phe (AGF), and Ile-Tyr-Pro (IYP) were identified and synthesized. Besides, FH reduced the contents of MMP-1 and MMP-3 in HaCaT cells, combining them effectively in molecular docking analysis. Thus, peptides from Pinctada martensii meat showed anti-photoaging activities and might have the potential to be used as an anti-photoaging agent in functional foods.

In this study, polysaccharides from Laminaria japonica (LJP) were produced by the treatment of ultraviolet/hydrogen peroxide (UV/H2O2) degradation into different molecular weights. Then, the degraded LJP were used to prepare LJP/chitosan/PVA hydrogel wound dressings. As the molecular weight of LJP decreased from 315 kDa to 20 kDa, the swelling ratio of the LJP-based hydrogels rose from 14.38 ± 0.60 to 20.47 ± 0.42 folds of the original weight. However, the mechanical properties of LJP-based hydrogels slightly decreased. With the extension of the UV/H2O2 degradation time, the molecular weight of LJP gradually decreased, and the anti-inflammatory activities of LJP-based hydrogels gradually increased. LJP that were degraded for 60 min (60-gel) showed the best inhibition effects on proinflammatory cytokines, while the contents of TNF-α, IL-6, and IL-1β decreased by 57.33%, 44.80%, and 67.72%, respectively, compared with the Model group. The above results suggested that low Mw LJP-based hydrogels showed great potential for a wound dressing application.

Pores, fractures, caves, and other storage spaces are commonly distributed in fractured-vuggy carbonate reservoirs. During the drilling process, more than half of all drill-in fluid loss issues are caused by developed caves. Cave scales range from centimeters to meters, making leak prevention increasingly difficult through the use of traditional technologies. Currently, there is still high demand for the understanding of feasible loss control techniques, especially in fractured-vuggy carbonate reservoirs. Multistage Bridge Plugging (MBP) technology has facilitated pioneering experiments in many oilfields, but the success rate of plugging is less than 50%, and the effects of plugging are uncontrollable and difficult to predict. This is due to a lack of clarity regarding the plugging mechanism and the key controlling factors. In this study, we used the Discrete Element Method (DEM) simulation method to investigate the controlling factors of MBP technology, and analyzed its applicable conditions. We found that the prerequisite for the success of MBP is the presence of a constricted throat near the wellbore when drilling the well hole; the first-stage bridging ball is the key to the success of MBP. Larger ball radius, cave inclination and initial flow rate, and lower ball velocity are beneficial to the first-stage bridging. All discussion in this research is based on the ideal situation. However, the cave pattern is difficult to describe using several models, let alone by one ideal model. With the progress of seismic fine description technology and mud logging, more accurate characterization of caves in carbonate reservoirs will help to accurately formulate the plugging scheme and greatly improve the success rate of plugging technology. Additionally, the engineering risks of this technology, such as plugging the coiled tubing, need to be further studied.

Natural antioxidants possess health beneficial properties and are being substantially used in foods, cosmetics and pharmaceutical products. Polyphenolics content, antioxidant activity and HepG2 liver cancer cells’ inhibition potential were determined and compared in the fruit of apricot cultivars collected from lower Himalayan region of Pakistan using standard analytical procedures. Comparatively, fruit of AP3 cultivar had highest levels of total phenolics and total flavonoids contents (220.5 ± 15.9 mgGAE/100 g and 382.0 ± 18.0 mgQE/100 g, respectively) on fresh weight basis. Fruit of the same cultivar had maximum DPPH scvenging potential (94.24 ± 4.55%), oxygen radicals absorbance capacity at 4.71 ± 0.12 mMolTE/100 g and inhibition of HepG2 cancer cells (45.80 ± 4.01 µMolQE/100 g). Though, fruit of AP4 cultivar was rich in vanillic acid, caffeic acid, vanillin, epi-catechin and quercetin, but had relatively low antioxidant and anticancer potential. Disparities in the phytochemical composition and properties of apricot fruit are attributed to genetic differences and growing conditions. Total phenolics, total flavonoids and caffic acid depicted highly significant positive association (˃90%) with ORAC, CAA and FRAP. Our findings suggest that being a rich source of health beneficial secondary metabolites, apricot fruit of Himalayan region of Pakistan could contribute considerably in socio-economic development of the local communities and as a functional food in regional and global markets.

In this paper, the Lower Silurian Longmaxi shale samples and the backflow fracturing fluid in the Changning Block of the Sichuan Basin were selected to investigate the damage mechanism of retained fracturing fluid to fractures in shale gas reservoirs. Thus, experiments were conducted on fracturing fluid backflow and gas-driving fracturing fluids. The changes of liquid permeability of shale samples, solid particle size distribution and turbidity of the backflow fracturing fluid were monitored. The gas permeability before and after fracturing fluid gas drive was compared, and the damage degree and mechanism of the backflow fracturing fluid to the fractures in shale samples were analyzed. And the following research results were obtained. First, the damage rate of shale permeability after the fracturing fluid backflow is between 53.1% and 97.6%, and the range of the solid particle size of the flowback fluid is significantly reduced. The main reservoir damage modes include phase trapping damage caused by liquid phase retention, blockage caused by the solid phase residue, particle migration induced by gas-carrying liquid and salt precipitation. Second, in the stage of gas phase flow, the damage rate of permeability drops to 23.1–80.2%, and the damage caused by liquid phase retention is relieved, but the damage caused by the blockage of solid phase residue and the salt precipitation of flowback on the facture surface is inevitable. Third, based on the damage mechanism of fracturing fluid backflow in shale gas wells to fractures, considering the treatment difficulty of the flowback and its damage to reservoir fractures, it is recommended to give a full play to the fracturing capacity of fracturing fluid and optimize the properties and dosages of fracturing fluid so as to reduce the flowback of fracturing fluid as much as possible. Keywords: Flowback of fracturing fluid, Shale gas, Reservoir damage, Solid phase retention, Water phase trapping, Particle migration, Salt precipitation, Sichuan basin, Changning block, Early silurian

It is difficult to stimulate coal reservoirs in physical approaches, and the recovery factor of coalbed methane (CBM) can be enhanced by applying strong oxidizers through oxidation to stimulate coal reservoirs. At present, however, there have been very few studies on the oxidation of CBM and fewer experimental studies for systematically evaluating the effect of oxidation on the seepage capacity of coal reservoirs. In this paper, the coal samples taken from coal seams of the Jurassic Xishanyao Formation in the Heishan Coal Mine, Toksun, Xinjiang, were selected as the study objects. Hydrogen peroxide solution immersion experiments were carried out on columnar and powdered coal samples, respectively to measure the permeability of columnar coal samples, the dissolution rate of powdered coal samples and the property parameters of hydrogen peroxide solution. Then, the reaction mechanisms between coal samples and hydrogen peroxide and the mechanisms to improve the seepage capacity of coal reservoirs were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectrum and wetting angle measurement. Finally, the stimulation effect of oxidation was compared with that of acidification. The following research results were obtained. (1) The permeability of coal samples is increased significantly after oxidation to 1.4–3.2 times the original permeability. (2) A large number of micro-fractures and dissolved pores are formed in the coal samples after oxidation, and consequently pore connectivity is improved greatly. Thus, the amount of associative hydroxyl and carboxyl functional groups on the surface of the coal samples increases, and the water wettability on the surface reduces. (3) Organic matters and pyrites are oxidized and consumed easily, and the generated H+ and micro-molecular aliphatic acids further dissolve inorganic mineral components. (4) Oxidation also has the advantage of acidification for dissolving inorganic mineral components, so there is a low and controllable probability of generating coal powder. In conclusion, applying strong oxidizers has the potential to become a new technology for coal reservoir stimulation. Keywords: Coal rock, Oxidation, Permeability, Pore connectivity, Acidification, Micro-fracture and dissolved pore, Dissolving inorganic minerals, Coal reservoir stimulation

In this study, a polysaccharide-based hydrogel microsphere (SFP/SA) was prepared using S. fusiforme polysaccharide (SFP) and sodium alginate (SA). Fourier transform infrared spectroscopy (FT-IR) demonstrated that SFP was effectively loaded onto the hydrogel microsphere. Texture profile analysis (TPA) and differential scanning calorimetry (DSC) showed that, with the increase of SFP concentration, the hardness of SFP/SA decreased, while the springiness and cohesiveness of SFP/SA increased, and the thermal stability of SFP/SA improved. The equilibrium adsorption capacity of SFP/SA increased from 8.20 mg/g (without SFP) to 67.95 mg/g (SFP accounted 80%) without swelling, and from 35.05 mg/g (without SFP) to 81.98 mg/g (SFP accounted 80%) after 24 h swelling. The adsorption of crystal violet (CV) dye by SFP/SA followed pseudo-first order and pseudo-second order kinetics (both with R2 > 0.99). The diffusion of intraparticle in CV dye was not the only influencing factor. Moreover, the adsorption of CV dye for SFP/SA (SFP accounted 60%) fit the Langmuir and Temkin isotherm models. SFP/SA exhibited good regenerative adsorption capacity. Its adsorption rate remained at > 97% at the 10th consecutive cycle while SFP accounted for 80%. The results showed that the addition of Sargassum fusiforme polysaccharide could increase the springiness, cohesiveness and thermal stability of the hydrogel microsphere, as well as improve the adsorption capacity of crystal violet dye.

Salt precipitation and its induced problems are increasingly prominent with the development of deep and ultra-deep tight sandstone gas reservoirs with high salinity formation water. In this paper, the change of porosity and permeability of a series of tight sandstone was measured, and then the morphology and occurrence state of crystalloid salt within the pore was observed by SEM. Meanwhile, high-pressure mercury injection analyzed the changes of pore size distribution. Experimental results show that salt precipitation could affect the porosity and permeability, which decreases by 53% and 65% after salt precipitation, respectively. The occurrence state of the crystalloid salt can be divided into three models: superposition growth along with the intergranular pore-fractures/natural micro-fractures, lamellar growth attached to the surface of the hydrophilic mineral like I/S interstratified mineral and the individual particles located in the corner of the pore. When the size of crystalloid salt is closer to the pore size distribution of tight sandstone, it will cause cracks and pore throat blockage easily. It is suggested that salt wash pretreatment should be carried out before analysis of tight sandstone with porosity less than 5%. Keywords: Salt precipitation, Tight sandstone, Porosity, Permeability, Formation damage

Nowadays, obesity in humans is a huge challenge requiring effective, readily available, and low-risk alternative treatments. Intake of edible Non-Digestible Polysaccharides (NDPs) is regarded as a promising strategy to combat obesity. Herein, an overview of the behavior of NDPs in the Gastrointestinal (GI) tract and its association with anti-obesity effect is summarized. Both the in vitro and in vivo of such investigations are discussed. Results show that NDPs can reach the large intestine to mediate the gut microbiota with the extent of regulation varies among NDPs with different chemical structures. The possible anti-obesity mechanisms associated with behavior of NDPs in the GI tract include: (i) inhibition of fat absorption, (ii) modification of gut microbiota and their metabolites such as short-chain fatty acids, (iii) regulation of bile acid profiles, (iv) modulation on appetite and satiety effect, and (v) protection of intestinal barrier. However, more efforts are required to clarify the exact behavior and their beneficial effects of NDPs within GI tract. This paper will provide an overlook of recent advances for better understanding anti-obesity activity of NDPs. •An overview of in vitro and in vivo studies on the behavior of edible Non-Digestible Polysaccharides (NDPs) in the Gastrointestinal (GI) tract is presented. •The anti-obesity mechanisms of NDPs based on their GI behavior are discussed.

The study explored the changes of a sulfated polysaccharide (SP) from Gracilaria Lemaneiformis during simulated human digestive system. The results showed SP was scarcely degraded without significant difference. Moreover, the results of fermentation in vitro indicated 53.7% of SP were utilized by gut microbiota with the molecular weight decreasing by 59.41% at 48 h. Meanwhile, 50.07 ± 2.82 mM of short chain fatty acids were produced in culture medium. Besides, in contrast with the regulation of galacto-oligosaccharide sacrificing diversity and richness of community, SP could regulate the composition of microbiota in a mild way. What’s more, Proteobacteria and Firmicutes were the most sensitive phyla responding to changes of pH values in this study. And Sutterella, Phascolarctobacterium, Parabacteroides, Lachnospiraceae_UCG-004, Desulfovibrio and Bacteroides were dominant genera for degrading and utilizing SP. Furthermore, the metagenomic function characteristics of microbes might be changed by SP. Thus, SP could be a potential prebiotic.

Capillary pressure curve plays a critical role in the reservoir evaluation. It is essential to reconstruct and predict capillary pressure curve properly. Many traditional capillary pressure correlations have been suggested in the literature. However, their major limitation is mainly applicable to homogenous reservoir, and the larger error will be caused when heterogeneous reservoir is dealt by using these mathematical correlations. This study aims at providing an important method based on Particle Swarm Optimization-Back Propagation Neural Network (PSO-BP neural network) to represent and predict capillary pressure curve for homogenous and heterogeneous reservoir. The combination of PSO algorithm and BP neural network converges quickly, which improves the accuracy and efficiency of simulation. In this paper, core samples from three blocks of the same marine-sand reservoir, whose porosity is between 0.6% and 20.0% and permeability is between 0.1mD and 6117mD, are investigated by PSO-BP neural network method and J-Function method respectively. The reconstruction and prediction results are compared with the results obtained by mercury intrusion method in laboratory. The results show that capillary pressure curves reconstructed and predicted by PSO-BP neural network method are in better agreement with mercury intrusion curves than J-Function method, with 0.1%–5% and 5%–8% relative error respectively, which can totally meet the in-situ requirements. It is also demonstrated that PSO-BP neural network method is more suitable for homogenous and heterogeneous reservoir. Keywords: Capillary pressure curve, Homogenous reservoir, Heterogeneous reservoir, PSO-BP neural network, Mercury intrusion

Sargassum fusiforme polysaccharide (SFP) was extracted from Sargassum fusiforme by hot water boiling, concentration and ethanol precipitation. The composition was determined as 58.10 ± 2.12% carbohydrate, 1.01 ± 0.15% protein, 9.85 ± 0.96% sulfate group and 17.66 ± 0.54% glucuronic acid. The average molecular weight of SFP was 224 kDa. The monosaccharide composition of SFP was 43.2% L-fucose, 3.5% rhamnose, 18.4% galactose, 1.5% glucose, 18.5% fructose, 5.9% xylose and 9.0% mannose respectively. SFP showed significant protective effect against ultraviolet B (UVB) radiation in hairless Kun Ming (KM) mice by manipulating the skin water content and thymus and spleen indexes. SFP could also alleviate UVB-induced oxidative stress by enhancing the activities of superoxide dismutase (SOD) and catalase (CAT) and reducing the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) equivalents. The levels of matrix metalloproteinase (MMP)-1 and 9 were also suppressed in SFP treatments. These findings suggest that SFP could be used as a potential functional food supplement for skin protection.

In order to evaluate the release of phenolics and the changes in antioxidant activities, fruits of Crataegus pinnatifida were subjected to in vitro digestion including simulated oral, gastric, small/large intestine digestion. Results showed that totally 37.41 ± 3.09 and 31.51 ± 2.35 mg GAE/g fruit, DW of phenolics were released for Shanlihong and Dajinxing, respectively, and the phenolics released were mainly flavonoids. Catechin, chlorogenic acid, procyanidine B2, epicatechin, paracoumaric acid, hyperoside and isoquercitrin were identified in the soluble fractions by high-performance liquid chromatography (HPLC). Results indicated that procyanidine B2, epicatechin, chlorogenic acid and catechin are four major released antioxidants. Oxygen radical absorption capacity and rapid peroxyl radical scavenging capacity were significantly positive-correlated with the release amount of total phenolics or flavonoids, demonstrating the major roles of phenolics and flavonoids in antioxidant activities. Our results implied that Shanlihong and Dajinxing could be considered as good sources of natural antioxidants.

By horizontal well multi-staged fracturing technology, shale rocks can be broken to form fracture networks via hydraulic force and increase the production rate of shale gas wells. Nonetheless, the fracturing stimulation effect may be offset by the water phase trapping damage caused by water retention. In this paper, a technique in transferring the negative factor of fracturing fluid retention into a positive factor of changing the gas existence state and facilitating shale cracking was discussed using the easy oxidation characteristics of organic matter, pyrite and other minerals in shale rocks. Furthermore, the prospect of this technique in tackling the challenges of large retention volume of hydraulic fracturing fluid in shale gas reservoirs, high reservoir damage risks, sharp production decline rate of gas wells and low gas recovery, was analyzed. The organic matter and pyrite in shale rocks can produce a large number of dissolved pores and seams to improve the gas deliverability of the matrix pore throats to the fracture systems. Meanwhile, in the oxidation process, released heat and increased pore pressure will make shale rock burst, inducing expansion and extension of shale micro-fractures, increasing the drainage area and shortening the gas flowing path in matrix, and ultimately, removing reservoir damage and improving gas recovery. To sum up, the technique discussed in the paper can be used to “break” shale rocks via hydraulic force and to “burst” shale rocks via chemical oxidation by adding oxidizing fluid to the hydraulic fracturing fluid. It can thus be concluded that this method can be a favorable supplementation for the conventional hydraulic fracturing of shale gas reservoirs. It has a broad application future in terms of reducing costs and increasing profits, maintaining plateau shale gas production and improving shale gas recovery.

In this study, Sargassum fusiforme polysaccharide was purified using a DEAE-Sepharose fast-flow column to obtain Sargassum fusiforme polysaccharides fraction (SFP-P1). As expected, the SFP-P1 contains mainly carbohydrates (87%) with less than 1% protein. Within the carbohydrate, it contains about 10% sulfate and 18% uronic acids. SFP-P1 consisted of l-fucose (13.17%), galactose (4.28%), glucose (1.95%), xylose (5.50%), and mannose (75.10%) with an average molecular weight of 113 kDa. Mannose and l-fucose were two predominant monosaccharides. In addition, (1 → )-linked or (1 → 6)-linked, (1 → 2)-linked or (1 → 4)-linked and (1 → 3)-linked glycosyl linkages accounted for 1.62%, 60.69% and 37.69% of all linkages in the molecule, respectively. The glycosidic linkage types of SFP-P1 were proven to be → 3,6)-α-d-Manp(1 →, → 4)-α-d-GalAp(1 →, → 4)-β-d-Xylp(1 → and → 3,4)-α-d-GlcAp(1 →. The results indicated the SFP-P1 had cytoprotective activity against UVB-induced oxidative stress in HaCaT cells through stimulation of SOD, GSH-PX enzymes activities and ROS. Also SFP-P1 suppressed the UVB-induced expression of MMP-1 & MMP-9.

In order to explore the damage mechanisms and improve the method to evaluate and optimize the performance of formation damage control of oil-based drill-in fluids, this paper took an ultra-deep fractured tight gas reservoir in piedmont configuration, located in the Cretaceous Bashijiqike Fm of the Tarim Basin, as an example. First, evaluation experiments were conducted on the filtrate invasion, the dynamic damage of oil-based drill-in fluids and the loading capacity of filter cakes. Meanwhile, the evaluating methods were optimized for the formation damage control effect of oil-based drill-in fluids in laboratory: pre-processing drill-in fluids before grading analysis; using the dynamic damage method to simulate the damage process for evaluating the percentage of regained permeability; and evaluating the loading capacity of filter cakes. The experimental results show that (1) oil phase trapping damage and solid phase invasion are the main formation damage types; (2) the damage degree of filtrate is the strongest on the matrix; and (3) the dynamic damage degree of oil-based drill-in fluids reaches medium strong to strong on fractures and filter cakes show a good sealing capacity for the fractures less than 100 μm. In conclusion, the filter cakes' loading capacity should be first guaranteed, and both percentage of regained permeability and liquid trapping damage degree should be both considered in the oil-based drill-in fluids prepared for those ultra-deep fractured tight sandstone gas reservoirs.

Polysaccharides from Gracilaria lemaneiformis possess various beneficial bioactive functions, but the immunomodulatory activity remains incompletely known. In the present study, a new low molecular-weight sulfated polysaccharide named as GLP-2 was isolated from G. lemaneiformis. The chemical composition and structural characteristics of GLP-2 were determined by high-performance gel permeation chromatography (HPGPC), gas chromatography (GC), infrared (IR) spectrum, methylation and nuclear magnetic resonance (NMR) analyses. In addition, the immunomodulatory activity and underlying mechanism of GLP-2 were examined using murine macrophage RAW264.7 cells. The results indicated GLP-2 could significantly improve the proliferation and pinocytic capability of RAW264.7 cells, and promote the production of reactive oxygen species (ROS), nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) by activating iNOS, IL-6 and TNF-α gene expressions. These results suggested that GLP-2 could be developed as a potent immunomodulatory agent for use in functional foods and dietary supplements.

Shales (illite was the dominant clay mineral) of Silurian Longmaxi Formation in Sichuan Basin and Triassic Yanchang Formation in Ordos Basin were taken as subjects to examine the mechanisms of shale-water interaction, quantitative characterization of hydration force and potential field applications based on micro forces analyses. Mica sheet with composition and property very similar to illite was tested for micro forces between the crystal layers. In electrolyte solution, micro forces between mica-solution-mica system include DLVO (Derjaguin-Landau-Verwey-Overbeek) force and hydration force; when the electrolyte concentration was low, the tested curve agreed with the theoretical DLVO curve; when the electrolyte concentration was higher than the critical value and the distance between mica sheets was less than 5 nm, the tested curve deviated from the DLVO curve completely, and the hydration force became dominant. Quantitative analysis indicated that the hydration force decayed in a rapid double-exponential type with the growth of distance. Field applications indicate that strict control of water invasion and reducing the strength of hydration force are the keys in designing collapse-preventing drilling fluids; meanwhile, during the shut-in period of shale gas wells, shale-water interaction can induce and extend micro-cracks, further improving the stimulation effect of shale reservoirs. Key words: shale, hydration force, illite, wellbore collapse, well shut-in