Search

The optimal selection of fracturing interval for the exploitation of tight oil reservoirs is very important for formulating a development program. In this study, the reservoir quality and the reservoir fracability are evaluated, and the criteria for the optimal selection of the fracturing interval are established, using the tight reservoir in the the Qing I Member of Qingshankou Formation in the Daqingzijing Oilfield of China as the study site. The results indicate that the porosity, the oil saturation and the effective thickness of tight reservoir are keys to optimizing the fracturing interval. The brittleness index and the difference coefficient among the horizontal stresses in the reservoir have a strong influence on fracability. The stress difference coefficient in the reservoir is smaller and the reservoir develops microfractures, the complex mesh fractures are easier to occur during fracturing. The stress difference between the reservoir and the surrounding bed is small and the thickness of the surrounding bed is thin, it is easy to communicate with adjacent oil-bearing layers when fracturing.

Cerebral metabolic dysfunction is a critical pathological hallmark observed in the aftermath of traumatic brain injury (TBI), as extensively documented in clinical investigations and experimental models. An in‐depth understanding of the bioenergetic disturbances that occur following TBI promises to reveal novel therapeutic targets, paving the way for the timely development of interventions to improve patient outcomes. The 13C isotope tracing technique represents a robust methodological advance, harnessing biochemical quantification to delineate the metabolic trajectories of isotopically labeled substrates. This nuanced approach enables real‐time mapping of metabolic fluxes, providing a window into the cellular energetic state and elucidating the perturbations in key metabolic circuits. By applying this sophisticated tool, researchers can dissect the complexities of bioenergetic networks within the central nervous system, offering insights into the metabolic derangements specific to TBI pathology. Embraced by both animal studies and clinical research, 13C isotope tracing has bolstered our understanding of TBI‐induced metabolic dysregulation. This review synthesizes current applications of isotope tracing and its transformative potential in evaluating and addressing the metabolic sequelae of TBI. [ABSTRACT FROM AUTHOR]

Probiotics have been increasingly investigated for their role in alleviating symptoms of ulcerative colitis (UC), but the specific mechanism involved remains unclear. We investigated the alleviating effect of Bifidobacterium animalis A6 (BAA6) in UC through a mouse dextran sulfate sodium (DSS) model. When treated with a high dose of BAA6 (1 × 1010 cfu/ml), it was found that colitis symptoms were significantly alleviated, and mucosal damages experienced obvious relief. Moreover, a high dose of BAA6 effectively upregulated free fatty acid receptors 2 and 3 (FFAR2 and FFAR3) expression and butyric acid metabolism specifically. Furthermore, the supplement of BAA6 significantly suppressed pro‐inflammatory cytokines levels (interleukin‐13) and the expression of pore‐forming protein claudin‐2. The upstream regulatory genes of claudin‐2, such as STAT6, GATA4, Cdx2, were also significantly inhibited by BAA6. Collectively, this study concludes that BAA6 attenuated DSS‐induced colitis by increasing the levels of intestinal butyric acid, activating the butyric acid‐FFAR pathway, suppressing excessive proinflammatory response, and protecting the function of the colon epithelial barrier. [ABSTRACT FROM AUTHOR]

Cerebral ischemia activates neural progenitors that participate in brain remodeling following acute injury. Sphingosine‐1‐phosphate receptor (S1PR) signaling governs cell proliferation and mobilization, yet its potential impact on neural progenitors and stroke recovery remains poorly understood. The goal of this study was to investigate the impact of S1PR modulation on post‐stroke neurogenesis and functional recovery, using a S1PR modulator BAF312. Mice were subjected to 60 min middle cerebral artery occlusion (MCAO) and received BAF312 starting from day 3 after MCAO until the end of experiment. BAF312 facilitated motor function recovery in MCAO mice until day 14 after surgery. Flow cytometry analysis revealed that BAF312 treatment led to an increase of type A cells in subventricular zone (SVZ), but not other progenitor cell subsets in MCAO mice. We found an increase of BrdU incorporation in SVZ DCX+ cells from MCAO mice receiving BAF312 and augmented proliferation of DCX+ cells in cultured neurospheres isolated from SVZ tissues. Notably, a S1PR1 antagonist W146 abolished BAF312‐induced increase of SVZ type A cells from MCAO mice and proliferation of DCX+ cells in cultured neurospheres. Additionally, the benefit of BAF312 to improve neurogenesis and stroke recovery remains in Rag2−/− mice lacking of T and B cells. Our results demonstrate that S1PR modulation improves neurogenesis and functional recovery following brain ischemia. [ABSTRACT FROM AUTHOR]

In this paper, an optimal consensus-based event-triggered control strategy is proposed to coordinate multiple distributed energy resources (DERs) in a dc microgrid. In the proposed control strategy, the average bus voltage restoration and the proportional current sharing are integrated by transforming the coordinated control problem into an optimization problem. The proposed solution enhances the resilience of the controller strategy in extreme events with uncertain initial states. Accordingly, the proposed control strategy provides a sampled-data-based event-triggered mechanism considering the limited availability of communication resources, which reduces communication burdens and avoids Zeno behaviors. The sufficient conditions are demonstrated using the Lyapunov–Krasovskii functional method for maintaining the stability of the proposed control strategy. Several case studies are presented using the PSCAD/EMTDC platform and the results are discussed to validate the effectiveness of the proposed control strategy for enhancing the dc microgrid resilience. [ABSTRACT FROM AUTHOR]

Compared with centralized control, distributed control for microgrids offers higher reliability and scalability. However, distributed control faces severe problems for maintaining the microgrid cybersecurity, which is due to the absence of central controllers for monitoring participating generation unit activities. This article proposes an observer-based resilient distributed control for AC microgrids that estimates and compensates false data injection (FDI) attacks on sensors and actuators. The proposed resilient control relies on an integrated distributed control structure, which restores the rated frequency/voltage and offers the proportional active/reactive power sharing with reduced exchanges of control signals. The proposed control has no limitation on the number of disrupted DGs and does not need access to the attack information. The H∞ output feedback control is applied to guarantee the L2 -gain boundedness of the control system. Several case studies are presented to verify the effectiveness of the proposed resilient distributed control in the PSCAD/EMTDC platform. [ABSTRACT FROM AUTHOR]

The virtual synchronous generator (VSG) provides a promising way to increase the inertia of inverter-based microgrids. However, when multiple VSGs are parallel in the grid, severe oscillations may be incurred. To address this problem, this article proposes a secondary frequency control for distributed VSGs with low bandwidth communication. The control can damp the oscillations and restore the frequency to the rated value without changing the virtual inertia provided by the VSGs. In addition, the proportional active power sharing is achieved by event-triggered communication mechanism, thereby reducing the communication burden considerably. The stability and Zeno-free behavior of the proposed control strategy are demonstrated by the ultimately uniformly bounded (UUB) theory. Simulations are conducted to verify the effectiveness of the proposed control strategy on the PSCAD/EMTDC platform. [ABSTRACT FROM AUTHOR]

The distributed controller consisting of a voltage controller and a power controller is commonly employed on the secondary control layer in the DC microgrid. In this paper, a novel optimal control based on the PI consensus algorithm is proposed for multiple battery energy storages (BESs) in an islanded DC microgrid. Compared with the conventional distributed voltage controller, the proposed scheme improves the system robustness to time delays. The steady-state analysis is conducted to verify that the proposed scheme can take effect in case of time delays. The impact of the secondary controller on the dynamics of the system under time delays is investigated by the eigenvalue analysis. Simulation results confirm that favorable power sharing and DC voltage regulation as well as robustness to time delays achieved by optimal control in an islanded microgrid with multiple BESs and constant power load (CPL). [ABSTRACT FROM AUTHOR]

The conventional voltage observer based distributed control can make a tradeoff between voltage restoration and reactive power sharing. However, it suffers from estimation error when there exist input disturbances, such as initial values and communication delays. To address this problem, this paper proposes a novel distributed secondary control based on PI consensus algorithm. A voltage controller and a frequency controller are designed separately to realize the restoration of voltage/frequency and also accurate reactive/active power allocation. Moreover, a detailed small-signal model with PI consensus algorithm is established to show the impact of the proposed control strategy on the system stability. Compared with the conventional distributed control, the proposed control scheme is simpler with higher control accuracy under input disturbances. Simulations are conducted to verify the effectiveness of the proposed control strategy in an isolated ac microgrid. [ABSTRACT FROM AUTHOR]

For a distributed DC microgrid, the conventional voltage control highly relies on the accuracy of the voltage observer, and the observer will produce an estimation error under time delays. To address the problem brought by the voltage observer, this paper transforms the voltage control into an optimization problem and integrates it into the power sharing control based on the PI consensus algorithm. With the proposed optimal control, the DC bus voltage control and proportional power sharing of the energy storages can be realized in one controller, so that the controller structure is dramatically simplified and the control accuracy will not be affected by the time delay. In addition, to further improve the system stability to resist delay, scattering transformation is introduced in the distributed optimal controller. By constructing Lyapunov function, it has been proved that the stability of the controller under the time delay can be guaranteed. Simulations are conducted to verify the effectiveness of the proposed control strategy and the transformation with and without time delay. [ABSTRACT FROM AUTHOR]

Hybrid energy storage system (HESS) consisting of battery and supercapacitor (SC) is an effective approach to alleviate voltage stability problems brought by the fluctuation of renewable resources in a dc microgrid. This paper proposes a novel distributed control scheme for multiple HESSs based on a leaderless consensus protocol to realize the power splitting between batteries and SCs and thus regulate the dc bus voltage. Without assigning leaders among the batteries and SCs, each SC or battery has equal priority in participating in voltage or state of charge (SOC) regulation using only neighboring information exchange instead of global communication. This distributed approach makes the system robust against any physical failure or communication fault only if the remaining communication network is connected. Consensus for the state variable associated with the battery SOC, the SC terminal voltage, and the dc average bus voltage are all achieved in this scheme, and thus the voltage quality and the energy storage lifetime can be improved. In addition, the small-signal stability of a four-HESS system is investigated, and the impact of the control parameters on the system is analyzed. Simulations and experimental studies are conducted to demonstrate the effectiveness of the proposed control scheme in an islanded dc microgrid. [ABSTRACT FROM AUTHOR]

Unregulated charging of a large number of electric vehicles (EVs) simultaneously may cause electricity shortages and price spikes in the power market. This paper deals with the optimization of EV charging strategy using the priority sequence. Firstly, the evaluation indices such as the schedulable interval ratio, the emergency probability and the battery losses are proposed. Then a comprehensive evaluation system for the EV scheduling priority is established by adopting the entropy weight method to incorporate multiple indices. Based on the scheduling priority obtained, a double-hierarchical optimal model is proposed, taking into account the constraints such as the demand of the EV owner. Its upper objective aims to minimize the sum of the square of deviation between the actual and the required schedulable capacity of EV aggregator over every interval. The lower one minimizes the sum of EV scheduling priority sequence over the scheduling interval. Case studies with 100 EVs show that the hierarchical optimization model can assist EV aggregator in making effective charging scheme. It is also observed that better flexibility for dispatching EVs can be achieved using multiple indices with weights. [ABSTRACT FROM AUTHOR]

In this paper, a distributed cooperative control scheme, considering the state-of-charge balance and power limits of battery-storage units (BSUs) in the consensus protocol, is proposed to achieve the average bus voltage consensus in a dc microgrid with photovoltaics. The state variable defined in the consensus protocol enables all BSUs to charge or discharge together without introducing circulating currents among BSUs. Furthermore, by incorporating power limits of BSUs in the defined state variable, power violation of the BSUs can be prevented. The consensus-based distributed control only utilizes neighbor-to-neighbor communication to realize the global consensus, and, thus, avoids the single point of the failure compared to the conventional centralized control. Simulation and experimental results demonstrate the efficacy of the proposed method in an islanded dc microgrid under different testing scenarios. [ABSTRACT FROM AUTHOR]

For distributed heterogeneous energy storage systems (HESSs) in a dc microgrid, a virtual impedance droop (VID) control, composed of virtual resistance droop control and virtual capacitor droop control, can realize low- and high-frequency power sharing between a battery and supercapacitor (SC) automatically. However, it still suffers from voltage deviation. In this paper, a secondary voltage recovery (SVR) control is proposed for a battery and SC on the basis of VID control. The SVR control for batteries is designed to regulate the average bus voltage to the reference value, depending on the communication between neighboring batteries. Nevertheless, the SVR control for SCs is decentralized to facilitate fast recovery of the state of charge, in spite of the existence of leakage current. Detailed impedance characteristics analysis and small-signal stability analysis are performed to find that the proposed SVR control does not affect the power sharing dominated by the primary VID control and the system stability. Simulations for both a single HESS and multiple HESSs are conducted to verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

The hybrid energy storage system (HESS) plays an essential role in the shipboard medium-voltage dc (MVdc) system to provide backup power, buffer large load change, as well as improve power quality. In this paper, a novel virtual resistor and capacitor droop (VRCD) control is first proposed for HESS including battery, supercapacitor, and flywheel. It enables the generator and multiple types of energy storages (ESs) with different characteristics to respond to multiple-frequency unbalanced power instead of simple high-frequency and low-frequency power sharing by the conventional droop control method. A detailed design procedure for the VRCD control is presented. Also, the secondary state of charge recovery control is proposed to maintain high energy reserve of ESs for further power demand. Simulations are conducted to demonstrate the effectiveness of the control scheme proposed in a shipboard MVdc under particular loads fluctuation, such as the propulsion motor and the pulsed load. [ABSTRACT FROM AUTHOR]

Aim: To achieve enhanced anticancer efficacy by combined siPlk1 and curcumin (cur) therapy using α-lactalbumin (α-lac) nanocarrier delivery. Materials & methods: α-Lac was partially hydrolyzed into amphiphilic peptides, and then self-assembled into nanospheres (NS). Cur was loaded into their hydrophobic core during the self-assembly process. siPlk1-SH was cross-linked with the endogenous cysteines on the NS. CRGDK peptide was conjugated on NS to target integrins overexpressed in HeLa cells. Results & conclusion: The Cur and siPlk1 coloaded NS formulations possessed an enhanced tumor targeting and antitumor properties. Drugs were responsively released from disulfide bonds cross-linked RGD-NS/Cur/siPlk1 corresponding to the high intracellular glutathione concentrations of cancer cells. Both in vitro cell viability experiments and in vivo antitumor evaluations demonstrated that the codelivered nanosphere platform exhibited excellent tumor targeting and synergistic antitumor efficacy. [ABSTRACT FROM AUTHOR]

Recently, dc electric springs (dc-ESs) have been proposed to realize voltage regulation and power quality improvement in dc microgrids. This paper establishes a distributed cooperative control framework for multiple dc-ESs in a dc microgrid and presents the small-signal stability analysis of the system. The primary level implements a droop control to coordinate the operations of multiple dc-ESs. The secondary control is based on a consensus algorithm to regulate the dc-bus voltage reference, incorporating the state-of-charge (SOC) balance among dc-ESs. With the design, the cooperative control can achieve average dc-bus voltage consensus and maintain SOC balance among different dc-ESs using only neighbor-to-neighbor information. Furthermore, a small-signal model of a four dc-ESs system with the primary and secondary controllers is developed. The eigenvalue analysis is presented to show the effect of the communication weight on system stability. Finally, the effectiveness of the proposed control scheme and the small-signal model is verified in an islanded dc microgrid under different scenarios through simulation and experimental studies. [ABSTRACT FROM PUBLISHER]

In this study, pH-responsive microspheres loaded with multiple antioxidants were developed for intestine-specific delivery and exhibited synergistic activity. They consist of chitosan (CS)-coated microspheres made of TEMPO-oxidized Konjac glucomannan (OKGM) polymers, of which the carboxyl (COO − ) groups are cross-linked via ferric ions (Fe 3+ ), allowing the hydrophobic (β-carotene) and hydrophilic (anthocyanins) antioxidants to be simultaneously incorporated. CLSM images showed successful co-encapsulation of β-carotene and anthocyanins. The in vitro release kinetics of co-loaded CS-OKGM microspheres in simulated GI fluids indicated that the microspheres retain the dual antioxidants in an acidic gastric environment and release them at intestinal pH. Free radical scavenging experiments demonstrated that multiple antioxidants loaded into OKGM system had synergistic activity with enhanced stability against heat. The multi-functional CS-OKGM microspheres showed great potential for multiple antioxidants and intestine-specific delivery with enhanced stability. [ABSTRACT FROM AUTHOR]

Human pluripotent stem cell (hPSC)-derived endothelial cells and their progenitors are important for vascular research and therapeutic revascularization. Here, we report a completely defined endothelial progenitor differentiation platform that uses a minimalistic medium consisting of Dulbecco's modified eagle medium and ascorbic acid, lacking of albumin and growth factors. Following hPSC treatment with a GSK-3β inhibitor and culture in this medium, this protocol generates more than 30% multipotent CD34 + CD31 + endothelial progenitors that can be purified to > 95% CD34 + cells via magnetic activated cell sorting (MACS). These CD34 + progenitors are capable of differentiating into endothelial cells in serum-free inductive media. These hPSC-derived endothelial cells express key endothelial markers including CD31, VE-cadherin, and von Willebrand factor (vWF), exhibit endothelial-specific phenotypes and functions including tube formation and acetylated low-density lipoprotein (Ac-LDL) uptake. This fully defined platform should facilitate production of proliferative, xeno-free endothelial progenitor cells for both research and clinical applications. [ABSTRACT FROM AUTHOR]

Akkermansia muciniphila is well known for the amelioration of inflammatory responses and restoration of intestinal barrier function. The beneficial effect of A. muciniphila occurred through contacting Toll-like receptor 2 (TLR2) on intestinal epithelial cells by wall components. In this case, the downstream mechanism of pasteurized A. muciniphila stimulating TLR2 for ameliorated intestinal barrier function is worth investigating. In this study, we evaluated the effect of live and pasteurized A. muciniphila on protecting the barrier dysfunction of Caco-2 intestinal epithelial cells induced by lipopolysaccharide (LPS). We discovered that both live and pasteurized A. muciniphila could attenuate an inflammatory response and improve intestinal barrier integrity in Caco-2 monolayers. We demonstrated that A. muciniphila enhances AMP-activated protein kinase (AMPK) activation and inhibits Nuclear Factor-Kappa B (NF-κB) activation through the stimulation of TLR2. Overall, we provided a specific mechanism for the probiotic effect of A. muciniphila on the intestinal barrier function of Caco-2 cells. [ABSTRACT FROM AUTHOR]

β-Carotene is a natural antioxidant that is beneficial for human health. β-Carotene is well known for its aqueous insolubility and its sensitivity to environmental stimuli. To achieve the targeted delivery of β-Carotene to human intestine, a microgel system was developed. The microgel is made of oxidized potato starch polymers, which are obtained by chemical cross-link process by sodium trimetaphosphate (STMP). At pH < p I (WPI: pH 5), as in the acidic condition in stomach, the positively charged WPI emulsified β-Carotene nanoemulsion droplets were absorbed by the negatively charged starch microgel particles, which prevented the early release of β-Carotene in stomach. At pH > p I , as in the intestinal condition, WPI–β-Carotene nanoemulsion droplets and microgel particles both carry negative charges. Under this condition, β-Carotene will be released from microgel. In this study, we investigated the absorption capacity of β-Carotene nanoemulsion droplets by oxidized starch microgel particles of various degrees of oxidation (DO) and the cross-link density ( R cross-linker/polymer(w/w) ) is investigated as a function of pH and salt concentrations. We found that DO30% with R cross-linker/polymer(w/w) = 0.1 was the optimal gel type for nanoemulsion droplets absorption, and pH 3 and ionic strength of 0.06 M were the optimal conditions for nanoemulsion droplets absorption. The swelling capacity of the microgel particles rather than its ζ-potential was dominant in governing the absorption capacity. The in vitro release experiment under stimulated gastrointestinal fluids suggested that β-Carotene emulsions droplets remained stable at the gastric condition and were majorly released under the intestinal condition. The results suggested that the oxidized starch microgel could be used to prevent the early release of β-Carotene in the stomach and target delivery of them to the intestine. [ABSTRACT FROM AUTHOR]

• BCAAs can be regarded as serum biomarkers for obesity. • Luffa potentially suppressed bacterial BCAA biosynthesis. • Luffa -affected bacterial metabolites triggered tissue-specific BCAA catabolism. • Luffa improved circulating BCAA dysfunction via gut microbiota to attenuate obesity. High circulating branched-chain amino acid (BCAA) levels can be diagnosis indicators for obesity. Luffa cylindrica (luffa) is one of vegetables against obesity. However, whether the anti-obesity of luffa is associated with BCAA metabolism and gut microbiota remains unknown. Here, we used conventionally raised diet-induced obese (DIO) mice to prove dietary luffa could reduce higher circulating BCAA levels and upregulate the tissue-specific expressions of BCAA-catabolizing enzymes. Meanwhile, dietary luffa selectively decreased the relative abundances of g_Enterortabdus , g_Eubacterium_xylanophilum_group and g_Butyricicoccus that exhibited significantly positive correlations with BCAA levels, BMI and HOMA-IR. Bacterial functionality prediction indicated dietary luffa potentially inhibited bacterial BCAA biosynthesis for reducing BCAAs supplementation. More importantly, dietary luffa had no impacts on BCAA catabolism in germ-free-mimic DIO mice. Thus, dietary luffa improved BCAA dysfunction via gut microbiota to attenuate obesity. This study offers a novel insight into dietary intervention against obesity from the aspect of gut microbiota-amino acid metabolism. [ABSTRACT FROM AUTHOR]

Luffa cylindrica is a nutrient-dense vegetable with medical properties and can alleviate metabolic diseases. Numerous evidences demonstrated gut microbiota impacted the progress of nonalcoholic fatty liver disease (NAFLD). This study was to investigate the underlying mechanism of L. cylindrica supplementation against NALFD via gut microbiota from hepatic transcriptional and metabolic analysis. In diet-induced obese mice, we observed L. cylindrica supplementation (2 g/kg body weight) effectively alleviated high-fat diet-induced obese symptoms such as body weight, fat deposition, and insulin resistance. Notably, L. cylindrica supplementation significantly relieved hepatic steatosis and inflammation infiltration to decrease hepatic toxicity. RNA-sequencing analysis showed that 130 hepatic genes in total significantly altered responding to L. cylindrica supplementation. And signaling pathway analysis revealed that L. cylindrica supplementation down-regulated the transcriptional expressions of CD36 and Rxrg to inhibit hepatic lipid synthesis. Moreover, L. cylindrica supplementation increased the transcriptional expressions of Ass1, Cps1, Cth, Got1, Tat, and Gls2 to enhance amino acid levels (Gly, Ala, Pro, Val, Ile, Asn, Met, and Phe) and improve hepatic abnormal gluconeogenesis. Furthermore, in antibiotic-treated obese mice, L. cylindrica supplementation did not change these gene expressions along with the hepatic levels of lipid and amino acids. Taken together, L. cylindrica supplementation could effectively suppress hepatic steatosis in diet-induced obese mice through inhibiting lipid synthesis and enhancing amino acid levels in liver, which depended on gut microbiota. Thus, L. cylindrica might be one promising dietary supplementation targeting at gut microbiota to reduce NAFLD risk. [ABSTRACT FROM AUTHOR]

TEMPO-oxidized Konjac glucomannan (OKGM) was developed as new material for preparing vegetarian hard capsules. OKGM of different degrees of oxidation: DO30%, DO50%, and DO80% were prepared to select optimum DO for capsule formation. FT-IR results proved that the primary alcohol groups on KGM were oxidized into carboxyl groups. XRD analysis suggested that TEMPO-oxidation decreased the crystallinity of KGM. DO80% was considered as the optimum candidate for capsule preparation owing to its superior solubility, transparency and reduced viscosity. The hydrophilicity of OKGM films, measured by contact angle measurement, increased with increasing DO. The elongation at break and tensile strength of the OKGM films enhanced with increasing DO. In vitro drug dissolution profile of OKGM capsules showed that the shell rupture time of DO80% capsule is about 5–10 min, and 80% of the drugs were released within 30–45 min. Thus DO80% OKGM was qualified to be used for gastric soluble hard capsules. [ABSTRACT FROM AUTHOR]