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Abstract Background Myeloid-derived suppressor cells (MDSCs) are the major factor in gastric cancer (GC) immune evasion. Nevertheless, the molecular process underlying the expansion of MDSCs induced by tumor-derived exosomes (TDEs) remains elusive. Methods The levels of exosomal and soluble PD-L1 in ninety GC patients were examined via enzyme-linked immunosorbent assay (ELISA) to determine their prognostic value. To investigate the correlation between exosomal PD-L1 and MDSCs, the percentage of MDSCs in the peripheral blood of 57 GC patients was assessed via flow cytometry. Through ultracentrifugation, the exosomes were separated from the GC cell supernatant and detected via Western blotting, nanoparticle tracking analysis (NTA), and transmission electron microscopy (TEM). The function of exosomal PD-L1 in MDSCs was evaluated via immunofluorescence, Western blotting and flow cytometry in a GC cell-derived xenograft (CDX) model. Results The overall survival (OS) of GC patients in the high exosomal PD-L1 group was significantly lower than that of patients in the low exosomal PD-L1 group (P = 0.0042); however, there was no significant correlation between soluble PD-L1 and OS in GC patients (P = 0.0501). Furthermore, we found that the expression of exosomal PD-L1 was positively correlated with the proportions of polymorphonuclear MDSCs (PMN-MDSCs, r = 0.4944, P

Cachexia affects approximately 50–80 % of advanced cancer patients, particularly those with gastric cancer (GC). Therefore, early detection of cachexia is essential to prevent its progression. Targeting the gut microbiota may be a promising approach for preventing and treating cachexia in patients with GC. Chemotherapy significantly reduced gut microbiota diversity in GC patients. Specifically, the abundance of bacterial genera such as Bacteroides, Streptococcus, and Prevotella was increased in the gut of patients postchemotherapy, which was closely associated with the development of cachexia. Serum metabolic analysis revealed a strong link between specific microbes and metabolite in patients with chemotherapy-induced GC cachexia. We further constructed a random forest model based on the top 6 genera in terms of abundance for the prediction of chemotherapy-related GC cachexia development; this model had an area under the receiver operating characteristic curve (AUC) of 93.5 % [95 % confidence interval (CI), 86.6 %-100 %], with a specificity and accuracy above 75 %. Additionally, we identified Enterotoxin Bacteroides fragilis (ETBF) as a key factor in chemotherapy-induced GC cachexia. In an in vivo GC model, the colonization of ETBF in the intestines of mice significantly accelerated the muscle and adipose tissue consumption induced by chemotherapy, resulting in cachexia symptoms. Furthermore, ETBF damaged the intestinal mucosal barrier by disrupting cell connections and attracting M1 macrophages, which advances GC cachexia. In conclusion, our findings indicate that gut microbiota imbalance is crucial in GC cachexia development, suggesting potential biomarkers for early diagnosis. Clinical trial registration: http://www.chictr.org.cn, Identification No: ChiCTR2200064547

BackgroundThe global status of chronic kidney disease (CKD) is underestimated, particularly the burden on adolescents and young adults (early-onset, aged 15–39).ObjectiveWe aim to investigate the pattern and trend of early-onset CKD from 1990 to 2019.MethodsWe analyzed age-specific rates of early-onset CKD incidence, death, and disability-adjusted life years (DALY) using Global Burden of Disease Study 2019 data. We examined the global, regional, national, gender-based, age group-based, and temporal changes of early-onset CKD burden from 1990 to 2019, as well as proportional DALY attributions of various risk factors.ResultsFrom 1990 to 2019, the global age-specific incidence rate (per 100,000 population) significantly increased from 25.04 (95% confidence interval 18.51, 31.65) to 32.21 (23.73, 40.81) for early-onset CKD. However, the global age-specific death rate significantly decreased from 2.96 (2.76, 3.15) to 2.86 (2.61, 3.11), and the age-specific DALY rate remained stable. Regarding sociodemographic indexes (SDI), countries with middle SDI had the highest incidence rates and the fastest increasing trends, while those with low and low-middle SDI experienced the highest death and DALY rates. Women had a generally higher age-specific incidence rate than men, whereas men showed higher age-specific death and DALY rates. In addition, the burdens of CKD increased with age among adolescents and young adults. Moreover, the main attributable risk factors for DALY of early-onset CKD were high systolic blood pressure (SBP), fasting plasma glucose (FPG), and body mass index (BMI).ConclusionThe age-specific incidence rate of early-onset CKD increased significantly from 1990 to 2019, and the age-specific DALY rate remained stable. High SBP, high FPG, and high BMI were the primary risk factors. Targeted prevention and healthcare measures should be developed considering age, gender, and region.

Background/objective: As the pivotal cellular mediators of bone resorption and pathological bone remodeling, osteoclasts have emerged as a prominent target for anti-resorptive interventions. Pinocembrin (PIN), a predominant flavonoid found in damiana, honey, fingerroot, and propolis, has been recognized for its potential therapeutic effects in osteolysis. The purpose of our project is to investigate the potential of PIN to prevent bone resorption in ovariectomized (OVX) mice by suppressing osteoclast production through its underlying mechanisms. Methods: The study commenced by employing protein-ligand molecular docking to ascertain the specific interaction between PIN and nuclear factor-κB (NF-κB) ligand (RANKL). Subsequently, PIN was introduced to bone marrow macrophages (BMMs) under the stimulation of RANKL. The impact of PIN on osteoclastic activity was assessed through the utilization of a positive TRAcP staining kit and a hydroxyapatite resorption assay. Furthermore, the study investigated the generation of reactive oxygen species (ROS) in osteoclasts induced by RANKL using H2DCFDA. To delve deeper into the underlying mechanisms, molecular cascades triggered by RANKL, including NF-κB, ROS, calcium oscillations, and NFATc1-mediated signaling pathways, were explored using Luciferase gene report, western blot analysis, and quantitative real-time polymerase chain reaction. Moreover, an estrogen-deficient osteoporosis murine model was established to evaluate the therapeutic effects of PIN in vivo. Results: In this study, we elucidated the profound inhibitory effects of PIN on osteoclastogenesis and bone resorption, achieved through repression of NF-κB and NFATc1-mediated signaling pathways. Notably, PIN also exhibited potent anti-oxidative properties by mitigating RANKL-induced ROS generation and augmenting activities of ROS-scavenging enzymes, ultimately leading to a reduction in intracellular ROS levels. Moreover, PIN effectively abrogated the expression of osteoclast-specific marker genes (Acp5, Cathepsin K, Atp6v0d2, Nfatc1, c-fos, and Mmp9), further underscoring its inhibitory impact on osteoclast differentiation and function. Additionally, employing an in vivo mouse model, we demonstrated that PIN effectively prevented osteoclast-induced bone loss resultant from estrogen deficiency. Conclusion: Our findings highlight the potent inhibitory effects of PIN on osteoclastogenesis, bone resorption, and RANKL-induced signaling pathways, thereby establishing PIN as a promising therapeutic candidate for the prevention and management of osteolytic bone diseases. The translational potential of this article: PIN serves as a promising therapeutic agent for the prevention and management of osteolytic bone diseases and holds promise for future clinical applications in addressing conditions characterized by excessive bone resorption. PIN is a natural compound found in various sources, including damiana, honey, fingerroot, and propolis. Its widespread availability and potential for therapeutic use make it an attractive candidate for further investigation and development as a clinical intervention.

The presented fast-locking phase-locked loop (PLL) approach, driven by sliding mode control (SMC), aims to maintain defined design parameters and system stability while achieving faster frequency switching. By adding the SMC output control voltage to the tuning terminal of the voltage controlled oscillator (VCO), the PLL system achieves a higher absolute rate of change of the VCO output frequency during frequency hopping. Simulation results in Simulink demonstrate a significant reduction in locking time, from $40~\mu \text {s}$ in the conventional PLL to $5~\mu \text {s}$ in the proposed PLL, under identical conditions of loop bandwidth and charge pump current.

Abstract Objective To construct a new prediction nomogram to predict the risk of musculoskeletal pain in patients with primary osteoporosis who receive zoledronic acid intravenously for the first time. Method Clinical data of 368 patients with primary osteoporosis who received the first intravenous injection of zoledronic acid in our hospital from December 2019 to December 2022 were studied. Patients were divided into a musculoskeletal pain group (n = 258) and a non-musculoskeletal pain group (n = 110) based on the presence or absence of musculoskeletal pain 3 days after injection. Statistically significant predictors were screened by logistic regression analysis and the minimum absolute contraction and selection operator (LASSO) to construct a nomogram. The nomogram was evaluated by the receiver operating characteristic (ROC) curve, the calibration curve, the C-index, and the decision curve analysis (DCA) and verified in a validation cohort. Results The independent predictors of the nomogram were age, serum 25-hydroxyvitamin D, NSAIDs, prior Vitamin D intake, and BMI. The area under the ROC curve (AUC) was 0.980 (95% CI, 0.915–0.987), showing excellent predictive performance. The nomogram c index was 0.980, and the nomogram c index for internal verification remained high at 0.979. Moreover, calibration curves show that the nomogram has good consistency. Finally, the DCA showed that the net benefit of the nomogram was 0.20–0.49. Conclusion Musculoskeletal pain is a common symptom of APR in OP patients treated with intravenous zoledronic acid. Risk factors for musculoskeletal pain after zoledronic acid injection in OP patients were: non-use of NSAIDs, youth (

Osteoporosis, a prevalent osteolytic condition worldwide, necessitates effective strategies to inhibit excessive bone resorption by curbing osteoclast hyperactivation. Liquiritin (LIQ), an flavanone derivative employed in acute lung injury and rheumatoid arthritis treatment, possesses an unclear role in addressing excessive bone resorption. In this investigation, we found that LIQ demonstrates the ability to inhibit osteoclast formation and the bone-resorbing activity induced by RANKL. At a specific concentration, LIQ significantly attenuated NF-κB-Luc activity induced by RANKL and curtailed NF-κB activation in RANKL-stimulated RAW264.7 cells, resulting in reduced IκB-α breakdown and diminished nuclear NF-κB levels. Furthermore, LIQ markedly inhibited RANKL-induced NFATc1 activation, as evidenced by diminished NFATc1 luciferase activity, reduced NFATc1 mRNA levels, and decreased nuclear NFATc1 protein levels. Subsequent experiments demonstrated that LIQ effectively restrained the RANKL-induced elevation of intracellular calcium as well as reactive oxygen species. Additionally, LIQ exhibited a downregulating effect on the expression of osteoclast-specific genes, which include Acp5, Cathepsin K, Atp6v0d2, Nfatc1, c-Fos, and Mmp9. Notably, our findings revealed the potential of LIQ to counteract decreased bone density in mice that underwent ovariectomy. Collectively, the data indicate that LIQ impedes osteoclast formation triggered by RANKL and the subsequent reduction in bone mass by mitigating ROS levels and suppressing the Ca2+/MAPK-NFATc1 signaling pathway, suggesting its promising candidacy as a therapeutic agent for RANKL-mediated osteoporosis.

To solve the problem of local high frequency vibration during test and operation for thin-walled tail nozzles of aero-engine, on the basis of mechanical vibration theory and finite element method, the vibration characteristics of the thin-walled tail nozzle were analyzed by the three-dimensional finite element simulation method, the low-order natural frequency, vibration mode, and relative vibration stress were obtained. On the basis of the working speed and related exciting factors, through the analysis of frequency margin and the drawing of Campbell diagram, the cause of vibration resonance was found out. By considering the structure and loading characteristics of the thin-walled tail nozzle, several improvement schemes were proposed to increase the natural frequency and avoid the low-order harmful resonance. Through simulation calculation and comparative analysis, according to practical engineering experience and the limitation of overall aerodynamic performance, the local truncation scheme was obtained as the optimal improvement scheme. The analysis showed that, the proposed optimal plan is a very effective method to improve the low-order natural frequency, which could not only improve the low-order natural frequency effectively and without weight increasing, but also have little effect on the overall aerodynamic performance. The results could provide theoretical basis and technical guidance for the design and structural optimization of large-size thin-walled components of aero-engines.

ObjectiveThe objective of the study was to investigate the effectiveness of aflibercept and panretinal photocoagulation (PRP) in the treatment of proliferative diabetic retinopathy (PDR).MethodsA retrospective analysis was performed on 59 patients (59 eyes) with high-risk PDR who were treated with aflibercept and PRP between January 2018 and December 2019. The best corrected visual acuity (BCVA), central foveal thickness (CFT), and retinal vein diameter post-treatment were compared to those before the treatment.ResultsThe best corrected visual acuity (BCVA) at 6 months (0.49 ± 0.14 logMAR), 12 months (0.54 ± 0.15 logMAR), 18 months (0.48 ± 0.15 logMAR), and 24 months (0.51 ± 0.15 logMAR) post-treatment were superior to the pre-treatment measurement (0.65 ± 0.18 logMAR). The central foveal thickness (CFT) at 6 months (310.67 ± 52.53 μm), 12 months (295.98 ± 45.65 μm), 18 months (282.56 ± 43.57 μm), and 24 months (281.53 ± 51.16 μm) post-treatment were lower than the pre-treatment measurement (456.53 ± 51.49 μm); the retinal vein diameter at 12 months (310.13 ± 24.60 μm), 18 months (309.50 ± 31.58 μm), and 24 months (317.00 ± 27.54 μm) post-treatment were lower than the pre-treatment measurement (361.81 ± 30.26 μm).ConclusionAflibercept intravitreal injection and panretinal photocoagulation may morphologically reverse retinal vein diameter and venous beading in high-risk proliferative diabetic retinopathy.

It is well-established that the honeycomb sandwich composite structures are easily prone to damage under low-energy impact. Consequently, it would lead to a dramatic decrease in structural load-bearing capacity and a threat to overall safety. Both experimental and numerical simulations are carried out to investigate the impact damage behavior of honeycomb sandwich composite specimens. The damage mode, damage parameters, and contact force-time curves of three types of panel materials with T300, T700, and T800 are obtained under different impact energies of 10 J, 20 J, and 40 J by the drop-weight impact experiment. Moreover, digital image correlation (DIC) tests are used to measure the deformation and strain of the lower panel. The experimental results reveal that the degree of damage increases with increasing impact energy. Particularly, the T300 panel specimen exhibits visible fiber fracture when subjected to an impact energy of 40 J. The impact process involves matrix cracking, fiber fracture, and delamination of the upper panel occurring first, followed by immediate crush damage to the honeycomb core and, finally, slight fiber damage to the lower panel. Due to its higher strength, the T800 panel specimen exhibits the highest damage resistance compared to the T700 and T300 panel specimens. To consider the microscopic failure criteria and various types of contact during the impact process, a finite element model of honeycomb sandwich composites is established, and numerical simulation analysis of low-energy impact is performed to determine the damage mode, damage size, and contact-force curves. Comparative analysis demonstrates good agreement between the simulation and experimental results. The findings of this study provide valuable technical support for the widespread application of honeycomb sandwich composites in the aviation field.

The buckling failure of the afterburner cylinder is a serious safety concern for aero-engines. To tackle this issue, the buckling simulation analysis of the afterburner cylinder was carried out by using finite element method (FEM) software to obtain the buckling mode and critical buckling loads. It was found that the afterburner cylinder was susceptible to buckling when subjected to differential pressure or the compressive force of the rear flange. Buckling would occur when the differential pressure reached 0.4 times the atmospheric pressure or when the axial compressive force on the rear flange reached 222.8 kN. Buckling was also found at the front of the cylinder under the auxiliary mount load. Additionally, under various loads on the rear flange, buckling occurred in the rear section, with the buckling mode being closely related to the load characteristics. Based on the simulation results and structural design requirements, two structural improvements were proposed, including the wall-thickening scheme and the grid reinforcement scheme. FEM simulation analysis results showed that both schemes would improve the rigidity and stability of the afterburner cylinder. For the 0.3 mm increase in the wall thickness scheme, the critical buckling load increased by 17.86% to 66.4%; for the grid reinforcement scheme, the critical buckling load increased by 169% to 619%. Therefore, the grid reinforcement scheme had a stronger anti-buckling ability and was deemed the optimal solution. The findings of this paper could provide technical support for the structural design of large-sized and thin-walled components of aero-engines.

Water consumption has been one of the most important topics in the field of environment and economy. Even though the driving factors of water consumption have been well studied, it is still a daunting task to reveal the influence of the status of provinces in the entire supply chain. By combining the multi-regional input-output (MRIO) model and complex network theory, an inter-provincial virtual water transfer (V WT) network was constructed to analyze the overall structural characteristics of the network model and identify the structural roles of each province. The constructed inter-provincial V WT network exhibited the characteristics of a small-world network, that is, virtual water can be easily transferred from one province to another. Moreover, network analysis revealed that provinces with different positions in the V WT network played discrepant structural roles. Panel regression analysis was further used to quantify the impact of provincial structural roles on their water consumption. The results showed that water consumption in China largely depended on some structural role characteristics in the V WT network. Out-degree and out-strength characterizing the ability of direct exporting virtual water exerted significant positive influences, while in-closeness featuring the indirect virtual water importing rate had a significant negative effect on water usage. This indicated that adjusting the uneven provincial consumption structure, the direct production demand of downstream provinces and the indirect production activities in the supply chain would help reduce water consumption. Therefore, to come true the goal of water conservation in China, it would be necessary to improve the trade structure between direct and indirect exporters and importers in the entire supply chain.

Myocardial ischemia is common in aging population. This study investigates the protective effect of Sevoflurane on myocardial ischemia reperfusion injury (MIRI) and its underlying mechanism. A total of 87 patients with a history of myocardial ischemia who underwent abdominal surgery with Sevoflurane general anesthesia were recruited in the study. The clinical data, blood pressure, heart rate, pressure-rate quotient (PRQ) and rate-pressure product (RPP) were recorded. Serum samples were collected and heart-type fatty acid binding protein (H-FABP), ischemia modified albumin (IMA), interleukin-1β (IL-1β), and interleukin-18 (IL-18) were measured to observe whether Sevoflurane anesthesia had protective effect on myocardium. In addition, MIRI rats and hypoxia/reoxygenation (H/R) injury cell model was established using neonatal rat ventricular myocytes (NRVM). Rats or NRVM were pretreated with sevoflurane for 45min before hypoxia. The mRNA expression of purinergic receptor-7 (P2X7) and NLR family pyrin domain containing 3(NLRP3) were examined. The protein expression of P2X7, NLRP3, apoptosis-associated speck-like protein (ASC), cysteine aspartic acid specific protease-1(Caspase-1), Gasdermin-D (GSDMD), Bcl-2 Associated X Protein (Bax), B-cell lymphoma-2 (Bcl-2) in myocardial tissue and cells were evaluated. The serum contents of IL-1β, IL-18, Malondialdehyde (MDA), Superoxide dismutase (SOD), Lactate dehydrogenase (LDH), Creatine kinase (CK), and Creatine kinase isoenzymes (CK-MB) were measured. The cellular localization and fluorescence intensity of NLRP3 and ASC in cells were detected. It was found that the secretion of IL-1β and IL-18 decreased in the patients. After I45 min/R3h in SD rats and H3h/R1h in NRVM, the protein expressions of P2X7, NLRP3, ASC, Caspase-1 and GSDMD were increased, the release of IL-1β, IL-18, CK, CK-MB, LDH and MDA were increased, and SOD activity was decreased. Sevoflurane treatment inhibited the high expression of P2X7, NLRP3, ASC, Caspase-1 and GSDMD, inhibited the release of LDH, CK,CK-MB and MDA in cells, and improved the activity of SOD, indicating that Sevoflurane alleviated the damage of MIRI of rats and H/R of NRVM, and had myocardial protective effect. Taken together, our study suggests that Sevoflurane inhibited the expression of IL-1β, IL-18 and GSDMD by inhibiting the P2X7-NLRP3 signaling pathway. It reduced the H/R injury of cardiomyocytes and protected the cardiac function by regulating inflammatory reaction and pyroptosis.

To overcome the space-time adaptive processing (STAP) performance loss caused by discarding the non-uniform parts of difference coarray and copulse for coprime sampling structure under the condition of single-frequency operation, this paper proposes a new STAP algorithm to improve the precision of filter weight vector estimation by the dual-frequency operation. By selecting a single proper additional operation frequency, we can obtain the different coarray and copulse, thus fill two missed virtual sensors and pulses of the difference structures in the single-frequency operation simultaneously. Compared with the single-frequency operation, the dual-frequency operation method can acquire the bigger uniform linear array (ULA) and coherent processing interval (CPI) pulse train to improve the system degrees of freedom (DOF), and result in higher angle-Doppler resolution. In addition, the coprime array has the little mutual coupling effect because of the larger inter-sensors spacing. Therefore, the resulting method can alleviate mutual coupling and enhance the system DOF.

Abstract Background Gestational diabetes mellitus (GDM) leads to poor pregnancy outcomes. Strategies that improve trophoblast cell function are important methods for GDM treatment. This study aimed to investigate the expression and diagnostic potential of microRNA-132 (miR-132) in GDM patients, and further analyzed the effects of miR-132 on HTR-8/SVneo cell proliferation. Methods Quantitative real-time PCR was applied to estimate the expression of miR-132. A receiver operating characteristics curve (ROC) analysis was performed to evaluate the diagnostic value of serum miR-132 in GDM patients. In vitro regulation of miR-132 in trophoblast cell HTR-8/SVneo was achieved by cell transfection, and the effects of miR-132 on cell proliferation were assessed using CCK-8 assay. Results Expression of miR-132 was decreased in serum and placenta tissues in GDM patients compared with the healthy women. A negative correlation was found between the serum miR-132 levels and fasting blood glucose of the GDM patients. A ROC curve shown the serum miR-132 had considerable diagnostic accuracy with an area under the curve (AUC) of 0.898. High glucose (HG) treatment induced an inhibition in HTR-8/SVneo cell proliferation and the expression of miR-132. The overexpression of miR-132 in HTR-8/SVneo cells could markedly rescued the HG - induced suppressed cell proliferation. Conclusion All the data of this study revealed the reduced expression of miR-132 in serum and placenta tissues of GDM, and serum miR-132 serves a candidate biomarker in the diagnosis of GDM. miR-132 may act a protective role against GDM via enhancing the trophoblast cell proliferation.

Diabetes nephropathy (DN) is the most common microvascular complications of diabetes, as hyperglycemia induces mesangial cell (MC) proliferation and inflammation and subsequently contributes to the development of renal fibrosis. Sphingosine kinase 1 (SphK1)/sphingosine 1-phosphate receptor 2 (S1P2) signaling pathway could activate AP-1 and NF-κB, which played a key regulatory role in the pathological progression of DN. This study investigates whether resveratrol (RSV) plays a regulatory role by SphK1/S1P2 pathway in MCs proliferation and inflammation under high glucose condition. Herein, we found that RSV inhibited MCs proliferation and attenuated high glucose (HG)-induced FN, TGF-β1, ICAM-1, iNOS, SphK1 and S1P2 expression and inhibited SphK1 activity andS1P production, which was also in accordance with MCs transfected with wild-type SphK1WT plasmid. Furthermore, RSV remarkably reduced AP-1 and NF-κB activation. Overall, these results indicated that RSV could be a potential and valuable resource of natural compounds for DN treatment via SphK1/S1P2 pathway.

In order to improve the surveillance effect of the aviation target surveillance radar, this paper improves the traditional filtering algorithm and builds the channel optimization system of the ADS-B aviation target surveillance radar based on the improved filtering algorithm. Moreover, this paper uses algorithm improvement to ensure the positive definite or semipositive definiteness of the state covariance and uses the root mean square volume Kalman filter to avoid the filter divergence or tracking interruption caused by the nonpositive definiteness of the matrix; the filtering principle of the interactive multimodel is to use multiple filters for parallel processing and achieve the adaptive adjustment algorithm residual error by adjusting the one-step prediction covariance in the adjustment algorithm. In addition, this paper combines the actual needs to construct a system functional structure to optimize the channel of the ADS-B aviation target surveillance radar and uses software engineering methods to model and analyze the requirements. Finally, this paper designs experiments to verify system performance. The research results show that the performance of the system constructed in this paper meets actual needs.

The rapid development of the Belt and Road economics has generated a considerable energy demand. Under the general trend of the global energy transition, natural gas resources are becoming the main driving force. The limited natural gas resources are posing a significant risk to economies, and this risk may also be transferred to other distant regions through economic trade. The aim of this study is to explore the trans-regional (sectoral) transmission pattern of natural gas scarcity risk. The main contribution of this paper is the assessment of the local natural gas scarcity risk (LGSR) and cross-region transfer relationship of embodied natural gas scarcity risk (EGSR), which are evaluated for the BRI economies. In addition, the network amplification effect is considered when evaluating the cross-regional impact of natural gas scarcity risk. The results show that, at the national level, Turkey, Ukraine, and Bulgaria have significant EGSR related to exports activities. The natural gas scarcity risks (GSRs) originating from these countries are mainly transferred to Turkmenistan, Georgia, and Albania, with large EGSR imports. Moreover, by comparing the ranking changes of EGSR imports, EGSR exports, and LGSRs at the national and sectoral levels, countries or sectors with higher LGSRs also have higher EGSR exports. The Top EGSR import and export network consisting of top EGSR flow relationships can well reflect countries’ preferences in choosing EGSR transfer partners. The results suggest that upstream countries and sectors should strengthen cooperation to manage natural gas resources, and provide references for decision makers in highly vulnerable downstream countries and sectors to formulate strategies to avoid the large-scale spread of economic losses caused by natural gas scarcity.

Adaptive orthogonal frequency division multiplexing (OFDM) technology is used in OFDM systems for broadband power line communications to effectively increase the communication rate. Existing research is mostly based on the single-layer network state for the resource allocation, and the required rate is often a static preset value. When there are significant differences in the signal-tonoise ratios of the sub-carriers, the system cannot adaptively adjust the required resources according to the quality-of-service (QoS) demand and the actual network, resulting in the waste of communication resources or the inability to meet some user communication needs. In this paper, a cross-layer resource allocation model is established for the system's cross-layer resource allocation problem through the data mapping among the application layer, data link layer, and physical layer. In the medium access control (MAC) layer, according to the quality of service (QoS) requirements of electric power multi-service, the data packet waiting delay and the packet loss are mapped to transmission rate proportionality constraints of real-time/non-real-time users through the utility function. A physical layer resource allocation model based on proportional constraints is constructed, and then an improved genetic algorithm is used for the resource allocation. Finally, through the simulation experiments in a typical power line channel environment, it is found that the proposed algorithm improves the total throughput by 4% ~ 6% over the existing two power line carrier resource allocation algorithms under the multi-service cross-layer resource allocation, and its proportional fairness is better. The proposed algorithm is able to maximize the system capacity while ensuring the QoS requirements, effectively improving communication quality. [ABSTRACT FROM AUTHOR]