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Abstract Background Chronic heat stress (CHS) is a detrimental environmental stressor with a negative impact on the meat quality of broilers. However, the underlying mechanisms are not fully understood. This study investigates the effects of CHS on long non-coding RNA (lncRNA) expression and muscle injury in broilers, with a focus on its implications for meat quality. Results The results showed that CHS diminished breast muscle yield, elevated abdominal fat deposition, induced cellular apoptosis (P

Abstract Background Wooden breast (WB) myopathy is a common myopathy found in commercial broiler chickens worldwide. Histological examination has revealed that WB myopathy is accompanied by damage to the pectoralis major (PM) muscle. However, the underlying mechanisms responsible for the formation of WB in broilers have not been fully elucidated. This study aimed to investigate the potential role of hypoxia-mediated programmed cell death (PCD) in the formation of WB myopathy. Results Histological examination and biochemical analysis were performed on the PM muscle of the control (CON) and WB groups. A significantly increased thickness of the breast muscle in the top, middle, and bottom portions (P

ABSTRACT: Wooden breast (WB) myopathy is a common myopathy found in commercial broiler chickens worldwide. Although extensive research on WB has been conducted using transcriptomics, effectively screening and analyzing key target information remains a challenge. In this present study, 5 transcriptomic datasets obtained from the National Center for Biotechnology Information (NCBI) were used. A meta-analysis was conducted to identify meta-differentially expressed genes (meta-DEGs) involved in the response of broilers to WB myopathy. These meta-DEGs were further analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and Gene Set Enrichment Analysis (GSEA), supplemented by protein-protein interaction (PPI) network construction to pinpoint hub genes. These analyses help to reveal key genes, pathways, and biological processes associated with WB myopathy. The results showed that 645 up-regulated and 99 down-regulated significant meta-DEGs (|log2FC| ≥0.6, P-Meta < 0.05, and present in at least 4 datasets) were identified. GO analysis showed that multiple fibrosis-related pathways/biological processes, such as cell adhesion, connective tissue development, and collagen-rich extracellular matrix, as well as calcium ion binding were significantly upregulated. PPI analysis identified TGFB3, COL1A1, COL1A2, and COL3A1 as central hub genes involved in the fibrotic processes. KEGG analysis revealed significant upregulation of apoptosis and lysosomal pathways, with an enrichment of Ca2+-related signals and lysosomal cathepsins within the apoptosis pathway. Additionally, GSEA indicated a suppression of the tricarboxylic acid (TCA) cycle and the mitochondrial electron transport chain (ETC) in WB myopathy, with PPI analysis also identifying specific hub genes associated with these pathways.In conclusion, our comprehensive analysis of meta-DEGs elucidated key biological processes and pathways implicated in WB myopathy, including fibrosis, apoptosis, altered calcium signaling, and metabolic disruption. The identification of specific hub genes offers avenues for further investigation into the pathogenesis of this condition, potentially guiding targeted therapeutic strategies.

ABSTRACT: This study aims to develop an experimental model of high lactate levels in broilers to mimic the condition of birds under stress or diseases and evaluate its consequent effects on meat quality. The injection sites and dosage effects were compared separately in 2 experiments. Experiment 1 includes 3 injection sites: intraperitoneal injection, intramuscular injection, and subcutaneous injection. Experiment 2 was a dosage experiment based on the results of Experiment 1: sodium lactate intraperitoneal injection group with 1.5, 3, 6 mM concentration. The results showed that injecting sodium lactate intraperitoneally, intramuscularly, or subcutaneously all significantly decreased body weight and breast muscle weight while elevating lactic acid levels in both the blood and breast muscle of broilers. Moreover, all 3 injection methods caused a significant reduction in pH24h and an increase in the shear force value of breast muscle. In addition, dose-response experiments of intraperitoneal injection showed that a concentration of 3 mM and 6 mM were significantly decreased body weight and breast muscle weight in broiler chickens, accompanied by a notable increase in breast muscle lactate content. Compared to the control group, intraperitoneal injections of 1.5 mM, 3 mM, and 6 mM sodium lactate treatments significantly reduced the yellowness values of the breast muscle. As the dose of sodium lactate increased, the shear force value of the breast meat exhibited linear and quadratic increments, while the drip loss decreased linearly. Intraperitoneal injection of 3 mM sodium lactate also significantly reduced the pH24h of broiler breast muscle. In addition, an increased dose of lactate injections up-regulated the glycolytic pathway responsible for endogenous lactate production in the breast muscle by upregulating the expression of phosphofructokinase, pyruvate kinase and lactate dehydrogenase A. In conclusion, intraperitoneal injection of sodium lactate at 3 mM directly increased breast muscle lactate levels, providing a valuable method for establishing a high-level lactate model in poultry.

Abstract As cities have grown, conductor rail power supplies have been widely used in the field of urban rail transit. In order to improve the running performance of trains and reduce the occurrence of accidents, it is necessary to understand the vibration of shoegear-rail system under different initial contact forces and explore the dynamic performance of shoegear-rail system. Therefore, according to the structure of shoegear-rail system, a coupling model of shoegear-rail system is established in this paper. On the basis of the model, the numerical simulation of the shoegear-rail system under different initial contact forces is carried out, and finally the vibration data of the shoegear-rail system under different initial contact forces are obtained. The results show that with the increase of initial contact force in the range of 70–160 N, the vibration amplitude of the electric shoegear and the fluctuation amplitude of the contact force increase, but the maximum absolute shear force value of the conductor rail decreases. It indicates that the lower initial contact force, the better the performance of shoegear-rail system.

ABSTRACT: This experiment aimed to reveal the dynamic changes of protein post-translational lactylation modifications and their correlations with the glycolytic process in broiler breast muscle within 48 h of postmortem acidification. The experiment involved 12 male AA broilers, 42 days old, with similar body weights (2.8 ± 0.05 kg). The breast fillets (Pectoralis major) were collected after slaughter, and samples were taken at various time points: 0, 15 min, 30 min, 45 min, 60 min, 2 h, 4 h, 6 h, 8 h, 12 h, 18 h, 24 h, 36 h, and 48 h postmortem. The results showed that the rate of glycogen decline in the muscle was highest at 45 min postmortem, and glycogen levels tended to stabilize at 8 h postmortem. The lactate content in the breast reached its highest level at 4 h postmortem and began to decrease, stabilizing at 24 h postmortem. Additionally, the glycolytic potential increased gradually in the first 4 h postmortem, decreased rapidly from 4 to 8 h. Similarly, lactylation modification levels were highest at 8 h postmortem, but stabilized at 12 h postmortem. During this process, the protein expression of the enzymatic lactylation modifier p300 showed no significant difference, while the content of the nonenzymatic lactylation substrate lactoylglutathione significantly decreased at 8 h and 24 h postmortem. Correlation analysis found that lactylation levels were negatively correlated with glycogen content, glucose content, glycolytic potential, and pH value, while positively correlated with lactate content. Besides, there was a positive correlation between lactylation levels and the protein expression of hexokinase, phosphoglycerate kinase 2, phosphoglucomutase 1, and triosephosphate isomerase. Additionally, lactylation levels were positively correlated with the activities of lactate dehydrogenase and phosphofructokinase. In summary, our experiment elucidated the dynamic changes in the entire glycolytic pathway in broiler pectoral muscle during acidification. During this process, lactylation modifications may participate in the glycolysis process by regulating the protein expression and activity of glycolytic enzymes.

ABSTRACT: Heat stress (HS) largely impairs the quality of broiler breast meat through protein oxidative modification. This study aimed to investigate the carbonylation pattern of Ca2+ channels and apoptotic proteins in the breast muscle of heat-stressed broilers. A total of 144 twenty-eight-day-old male Arbor Acres broilers were randomly divided into three treatment groups. The normal control (NC) group was kept at 22°C and provided with unlimited feed. The HS group was exposed to 32°C and provided with unlimited feed. The pair-fed (PF) group was kept at 22°C and given an amount of feed equivalent to that consumed by the HS group on the previous day. Results showed that broilers under HS conditions had a higher respiratory rate than those in NC and PF groups (P < 0.05). HS disrupted the morphology and structure of breast muscle fibers by decreasing the average diameters and average density of myofibers compared to the NC group (P < 0.05). HS increased the mean fluorescence intensity of the positive carbonyl signal in breast muscle compared with the NC group (P < 0.05). Besides, the pectoral Ca2+ concentration in the sarcoplasmic reticulum, cytoplasm, and mitochondria was elevated by HS when compared with the NC group (P < 0.05). In comparison to the NC and PF groups, HS increased the apoptosis rate and caspase-3 activity in the breast muscle (P < 0.05). Furthermore, HS elevated the relative protein expressions of plasma membrane Ca2+-ATPase, Na+/Ca2+ exchanger 1, and sarco/endoplasmic reticulum calcium transport ATPase 1 compared to the NC group (P < 0.05). Higher relative protein expression of μ-calpain and lower relative protein expression of cytosolic cytochrome complex were found in the HS group than the NC group (P < 0.05). HS decreased the carbonylation levels of transient receptor potential canonical 1 and inositol 1,4,5-trisphosphate receptor compared to the NC group (P < 0.05). Additionally, the carbonylation levels of cleaved caspase-3 and precursor caspase-9 were increased and decreased, respectively, by HS treatment compared to the NC group (P < 0.05). In conclusion, HS damages the myofiber based on Ca2+ dyshomeostasis and apoptosis, which are potentially associated with protein carbonylation. These results shed new light on the possible mechanism behind the development of poor meat quality in broilers due to HS.

A miniature single-piston valve flow-matching water-hydraulic pump is described in this paper, which designs with a unique double-face cam mechanism to achieve the reciprocating motion of the piston and a new flow-matching valve to adapt to the requirements of the frequency of flow-matching, and the use of a brushless DC motor to regulate the speed and control the flow of the pump. In this paper, the mechanical structure and working principle of this new type of water-hydraulic pump are described, the mathematical model of the valve flow distribution process is established, the transfer functions of the suction and drain process are obtained, and the relationship between the structural parameters of the distribution valve and the transient output characteristics of this type of water-hydraulic pump is simulated, and the simulation results show that the quality of the valve spool is the key factor affecting the switching speed of the distribution valve. The transient pressure and transient flow rate of the pump are studied experimentally, which reveals the pulsation law of the output characteristics of this single-piston pump, and lays a theoretical foundation for the design of a double-piston pulsation-free hydraulic pump.

The off-line discharge between the pantograph and catenary (PAC) occurs frequently in the actual operation of an electric locomotive, which affects the quality of the received current and the service life of the pantograph. The current experiments on the off-line discharge between the PAC are mainly low-power ones and the models established are static. To study the electrical behaviors during the PAC relative motion under the actual working conditions, in this paper, the voltage and current of the contact wire (CW) during its motion are measured. And the electrical behaviors during the rise, fall and reciprocating motions of the pantograph are investigated by combining a finite element method (FEM) model based on the magnetohydrodynamics with the auto transformer (AT) traction network circuit and moving mesh method. It is found that the harmonic frequencies are mainly in the range of 0-30 MHz. The voltage distortion is more obvious during the fall of the pantograph. And the negative polarity spike pulse has a larger amplitude and occurs more frequently. The novelty of this paper lies in the experimental test with the high current and high power, as well as the systematic analysis of the electrical behaviors and multi-physical field evolution during the motion of the pantograph under the working conditions. Its contribution is to present an effective method to study the dynamic behaviors of the PAC. The research results can provide an important reference for the identification of the electrical characteristics of the PAC and the protection of the PAC equipment.

The increase of the running speed of electric train has a certain influence on the dynamic performance of coupling of conductor rail and collector shoe. In this paper, the mechanical characteristics of coupling vibration between shoe and rail for high-speed trains are studied by using a numerical simulation method, and the effects of train speed on the vibration law of shoe-rail interaction system are analyzed. The results show that both the maximum displacement of the rail and the maximum contact force between the shoe and the rail increase with the increase of the train speed. The bending moment of the rail, the maximum displacement of the shoe, the elastic and viscous forces of the shoe all decrease first and then increase. In particular, when the train speed increases from 275 to 300 km/h, the displacement, bending moment, contact force, and other mechanical quantities increase significantly, which indicate that it will lead to a sharp increase in vibration degree when the train speed exceeds 275 km/h. Therefore, in the case of actual operating parameters in this paper, it is recommended that the train speed does not exceed 275 km/h.

ABSTRACT: Studies have demonstrated that chronic heat stress can accelerate glycolysis, decrease glycogen content in muscle, and affect muscle quality. However, the consequences of chronic heat stress on glycogen synthesis, miRNA expression in pectoralis major (PM) muscle, and its regulatory functions remain unknown. In this study, high-throughput sequencing and cell experiments were used to explore the effects of chronic heat stress on miRNA expression profiles and the regulatory mechanisms of miRNAs in glycogen synthesis under chronic heat stress. In total, 144 cocks were allocated into 3 groups: the normal control (NC) group, the heat stress (HS) group, and the pair-fed (PF) group. In total, 30 differently expressed (DE) miRNAs were screened after excluding the effect of feed intake, which were mainly related to metabolism, signal transduction, cell growth and death. Furthermore, the gga-miR-212-5p/GYS1 axis was predicted to participate in glycogen synthesis through the miRNA-mRNA analysis, and a dual-luciferase reporter test assay confirmed the target relationship. Mechanistically, chronic heat stress up-regulated gga-miR-212-5p, which could inhibit the expression of GYS1 in the PM muscle. Knocking down gga-miR-212-5p alleviates the reduction of glycogen content caused by chronic heat stress; overexpression of gga-miR-212-5p can reduce glycogen content. This study provided another important mechanism for the decreased glycogen contents within the PM muscle of broilers under heat stress, which might contribute to impaired meat quality.

The frequent occurrence of the pantograph–catenary (PC) arc seriously threatens the safe and stable operation of electric multiple units (EMUs). In order to investigate the primary factors affecting the electrical characteristics of the PC arc, this paper first reveals the mechanism of arc generation when EMUs leave the split-zone insulator according to the actual mechanical structure of the PC articulated split-zone insulator. Then, based on the Habedank black box arc model, considering the dynamic changes in arc length during the actual operation of EMUs, a numerical simulation model suitable for describing the PC articulated split-zone insulator arc is established. Furthermore, by comparing with existing research results, the effectiveness of the proposed model is verified. Next, a series of simulation experiments were conducted to analyze the influence of different operating parameters of the EMUs on the electrical characteristics of the PC arc. More importantly, the paper proposes using the entropy weight method to calculate the impact strength of different operating parameters of the EMUs on the arc duration time of the contact wire split-zone region. The research results of this paper can provide some technical references for reducing the erosion of the PC contact wire and slide caused by arcs when the EMUs pass through the split-zone insulator.

Abstract Rational design of self-assembled DNA nanostructures has become one of the fastest-growing research areas in molecular science. Particular attention is focused on the development of dynamic DNA nanodevices whose configuration and function are regulated by specific chemical inputs. Herein, we demonstrate the concept of metal-mediated base-pair switching to induce inter- and intramolecular DNA strand displacement in a metal-responsive manner. The 5-hydroxyuracil (U OH ) nucleobase is employed as a metal-responsive unit, forming both a hydrogen-bonded U OH –A base pair and a metal-mediated U OH –GdIII–U OH base pair. Metal-mediated strand displacement reactions are demonstrated under isothermal conditions based on the base-pair switching between U OH –A and U OH –GdIII–U OH . Furthermore, metal-responsive DNA tweezers and allosteric DNAzymes are developed as typical models for DNA nanodevices simply by incorporating U OH bases into the sequence. The metal-mediated base-pair switching will become a versatile strategy for constructing stimuli-responsive DNA nanostructures, expanding the scope of dynamic DNA nanotechnology.

Abstract Postoperative recurrence and metastasis are the main reasons for the poor prognosis of osteosarcoma (OS). Currently, an ideal predictor for not only prognosis but also drug sensitivity and immunotherapy responses in OS patients is urgently needed. Angiogenesis plays a crucial role in tumour progression, which suggests its immense potential for predicting prognosis and responses to immunotherapy for OS. Angiogenesis patterns in OS were explored in depth in this study to construct a prognostic model called ANGscore and clarify the underlying mechanism involved in the immune microenvironment. The efficacy and robustness of the model were validated in multiple datasets, including bulk RNA-seq datasets (TARGET-OS, GSE21257), a single-cell RNA-seq dataset (GSE152048) and immunotherapy-related datasets (GSE91061, GSE173839). OS patients with a high ANGscore had a worse prognosis, accompanied by the immune desert phenotype. Pseudotime and cellular communication analyses in scRNA-seq data revealed that as the ANGscore increased, the malignant degree of cells increased, and IFN-γ signalling was involved in tumour progression and regulation of the tumour immune microenvironment. Furthermore, the ANGscore was associated with immune cell infiltration and the response rate to immunotherapy. OS patients with high ANGscore might be resistant to uprosertib, and be sensitive to VE821, AZD6738 and BMS.345541. In conclusion, we established a novel ANGscore system by comprehensively analysing the expression pattern of angiogenesis genes, which can accurately differentiate the prognosis and immune characteristics of OS populations. Additionally, the ANGscore can be used for patient stratification during immunotherapy, and guide individualized treatment strategies.

ABSTRACT: Chronic heat stress has detrimental effects on the growth performance of broilers, and the potential mechanism is under exploration. In this study, the protein carbonyl modification was introduced to glycolytic enzymes to evaluate its relationship with the growth performance of heat-stressed (HS) broilers. A total of 144 male 28-day-old broilers were assigned to 3 treatments: the normal control group (NC, raised at 22°C with free access to feed and water), the HS group (raised at 32°C with free access to feed and water), and the pair-fed group (PF, raised at 22°C with an amount of feed equal to that consumed by the HS group on a previous day). Results showed that heat stress decreased the average daily growth, increased the feed-to-gain ratio (F/G), decreased breast muscle rate, and increased abdominal fat rate compared with the NC and PF groups (P < 0.05). Higher cloacal temperature and serum creatine kinase activity were found in the HS group than those of the NC and PF groups (P < 0.05). Heat stress increased the contents of carbonyl, advanced glycation end-products, malonaldehyde, and the activities of catalase, glutathione peroxidase, and total antioxidant capacity compared with the NC and PF groups (P < 0.05). Heat stress increased the contents of glucose and lactate, declined the glycogen content, and lowered the relative protein expressions of pyruvate kinase muscle type, lactate dehydrogenase A type (LDHA), and citrate synthase compared to those of the NC group (P < 0.05). In contrast to the NC and PF groups, heat stress intensified the carbonylation levels of phosphoglucomutase 1, triosephosphate isomerase 1, β-enolase, and LDHA, which were positively correlated with the F/G (P < 0.05). These findings demonstrate that heat stress depresses growth performance on account of oxidative stress and glycolysis disorders. It further increases the carbonylation of glycolytic enzymes, which potentially correlates with the F/G by disturbing the mode of energy supply of broilers.

ABSTRACT: Heat stress can cause systemic immune dysregulation and threaten the health of broilers. Guanidinoacetic acid (GAA) has been shown to be effective against heat stress, but whether it is beneficial for immunity is unclear.Therefore, the effects of dietary GAA supplementation on the immunity of chronic heat-stressed broilers were evaluated. A total of 192 Arbor Acres male broilers (28-day old) were randomly allocated to 4 treatments: the normal control group (NC, 22°C, ad libitum feeding), the heat stress group (HS, 32°C, ad libitum feeding), the pair-fed group (PF, kept at 22°C and received food equivalent to that consumed by the HS group on the previous day), and the GAA group (HG, 32°C, ad libitum feeding; basal diet supplemented with 0.6 g/kg GAA). Samples were collected on d 7 and 14 after treatment. Results showed that broilers exposed to heat stress exhibited a decrease (P < 0.05) in ADG, ADFI, thymus and bursa of Fabricius indexes, and an increase (P < 0.05) in feed conversion ratio and panting frequency, compared to the NC group. Levels of corticotropin-releasing factor, corticosterone (CORT), heat shock protein 70 (HSP70), IL-6, and TNF-α were elevated (P < 0.05) while lysozyme and IgG concentration was decreased (P < 0.05) in the HS group compared with the NC group after 7 d of heat exposure. The concentrations of IgG and IL-2 were decreased (P < 0.05) and CORT was increased (P < 0.05) in the HS group compared with the NC group after 14 d of heat exposure. Noticeably, GAA supplementation decreased the levels of CORT (P < 0.05) and increased the IL-2, IgG, and IgM concentrations (P < 0.05) compared with the HS group. In conclusion, chronic heat stress increased CORT release, damaged immune organs, and impaired the immunity of broilers. Dietary supplementation of 0.6 g/kg GAA can reduce the CORT level and improve the immune function of broilers under heat stress conditions.

A method was developed for the simultaneous determination of the residues and migration of 18 polycyclic aromatic hydrocarbons (PAHs) in food contact rubber by gas chromatography-mass spectrometry (GC-MS). The rubber extract was cleaned up by solid phase extraction (SPE) with a silica gel column. The migration solution was extracted with hexane, separated on a DB-EUPAH column (60 m × 250 μm, 0.25 μm), detected in the selective ion monitoring (SIM) mode, and quantified by an internal standard method. The results showed that good chromatographic separation of the 18 PAHs was achieved. The calibration curves showed good linearity in the concentration range of 0.05–0.5 mg/L. The limits of detection (LOD) were less than 0.01 mg/L, and the limits of quantification (LOQ) were less than 0.05 mg/L. The average recoveries for PAHs residues and migration at three spiked levels ranged from 61.3% to 102.2%, and the relative standard deviations (RSDs, n = 6) were 0.5%–9.1%. A total of 16 PAHs were detected in 10 of the 34 batches of food contact rubber tested with total residues ranging from 0.24 to 16.97 mg/kg. No PAHs were found to be migrated from the rubber to 4% acetic acid and 10% ethanol at different experimental temperatures. Many PAHs were found to be migrated to 50% ethanol as a food simulant. The number of PAHs migrated increased with an increase in temperature, and the rate and amount of migration increased significantly. The safety problems caused by the residues of PAHs in food contact rubber and their migration to foods cannot be neglected.

Abstract Acoustic sensors with ultrahigh sensitivity, broadband response, and high resolution are essential for high-precision nondestructive weak signal detection technology. In this paper, based on the size effect of an ultrahigh-quality (Q) calcium fluoride (CaF2) resonator, a weak acoustic signal is detected by the dispersive response regime in which an acoustic, elastic wave modulates the geometry and is converted to a resonance frequency shift. Through the structural design of the resonator, the sensitivity reaches 11.54 V/Pa at 10 kHz in the experiment. To our knowledge, the result is higher than that of other optical resonator acoustic sensors. We further detected a weak signal as low as 9.4 µPa/Hz1/2, which greatly improved the detection resolution. With a good directionality of 36.4 dB and a broadband frequency response range of 20 Hz–20 kHz, the CaF2 resonator acoustic sensing system can not only acquire and reconstruct speech signals over a long distance but also accurately identify and separate multiple voices in noisy environments. This system shows high performance in weak sound detection, sound source localization, sleep monitoring, and many other voice interaction applications.

Bi2Te3-based alloys are the most mature commercial thermoelectric (TE) materials for the cooling application near room temperature. However, the poor mechanical properties of the commercial zone melting (ZM) ingot severely limits the further application. Meanwhile, due to the donor-like effect, the robust polycrystalline n-type bulks usually have low TE performance near room temperature. Herein, based on the commercial ZM ingots, a high figure of merit (zT) of 1.0 at 320 K and good mechanical properties are achieved via the hot extrusion. The dynamic recrystallization in the hot-extrusion process can suppress the donor-like effect and refine the large ZM grains into fine-equiaxed grains. Moreover, the obtained polycrystalline Bi2Te2.79Se0.21 has good preferential orientation and high carrier mobility (μ). The high μ and the weaken donor-like effect maintain the high power factor (PF) of 43.1 μW cm−1 K−2 in the hot-extruded ZM sample. Due to the enhanced phonon scattering, the total thermal conductivity κtot decreased to 1.35 W·m−1·K−1. To demonstrate the good mechanical properties of the extruded ZM sample, micro TE dices with the cross sections of 300 μm × 300 μm and 200 μm × 200 μm are successfully cut from the extrusion sample. This study provided a fast and low-cost extrusion technique to improve the TE and mechanical properties of the commercial ZM ingot at room temperature.

The fatigue behavior of a high-strength bearing steel tempered under three different temperatures was investigated with ultrasonic frequency and conventional frequency loading. Three kinds of specimens with various yield strengths exhibited obvious higher fatigue strengths under ultrasonic frequency loading. Then, a 2D crystal plasticity finite element method was adopted to simulate the local stress distribution under different applied loads and loading frequencies. Simulations showed that the maximum residual local stress was much smaller under ultrasonic frequency loading in contrast to that under conventional frequency at the same applied load. It was also revealed that the maximum local stress increases with the applied load under both loading frequencies. The accumulated plastic strain was adopted as a fatigue indicator parameter to characterize the frequency effect, which was several orders smaller than that obtained under conventional loading frequencies when the applied load was fixed. The increment of accumulated plastic strain and the load stress amplitude exhibited a linear relationship in the double logarithmic coordinate system, and an improved fatigue life prediction model was established.

In a hydraulic system, a micro variable pump is required to be high pressure and high speed, and this work presents a new type of 2D bivariable pump structure in which the worm gear and worm mechanism are used to rotate the cylinder block to change the flow distribution state of the cylinder window and the piston groove to change the displacement of the 2D pump. The flow–pressure mathematical model of the 2D variable pump is established to analyze the relationship between pump displacement and the pump cylinder rotation angle and the effects of variable displacement on pump pressure characteristics, flow characteristics, and volume efficiency in Matlab. During the experiment, we tested the change in the corresponding pump output flow when the cylinder rotation angle is 0~12°, which verifies the correctness of the variable calculation model. The experimental results indicate that the volume efficiency and mechanical efficiency of the single-piston 2D pump are reduced to different degrees after variable displacement, the volume efficiency is reduced by approximately 3% at most, and the mechanical efficiency is reduced by approximately 5% at most.

Aluminum/graphite composites are receiving much attention due to the unique features and diverse possibilities in different fields. Generally, the aluminum melt into the inner pores of the graphite matrix requires an ambient prompting with high temperature and gas pressure. The infiltration dynamics of aluminum melt, which highly depends on the ambient temperature, would have a significant effect on the final composite’s performance. In this work, we have studied the temperature effect of aluminum melt during the infiltration process into the porous graphite matrix based on numerical simulation and experimental verification. Results show that the moderate temperature increase would effectively promote the infiltration of aluminum melt, achieving a higher filling rate with a shorter filling time. However, the promotion effects of the temperature increase would come to a certain limit due to the opposing effects of capillary porous and residual gas. The detailed influences of the temperature on the infiltration would be presented, and the final composite performance, including mechanical strength and thermal management capability, would be examined and discussed.

ABSTRACT: The incidence of wooden breast (WB) meat of commercial broiler chicken has been increasing in recent years. Histological examination found that the occurrence of WB myopathy was accompanied by the pectoralis major (PM) muscle damage. So far, the potential mechanisms are not fully understood. This study aimed to explore the underlying mechanism of the damage of WB-affected PM muscle caused by changes in mitochondrial function, mitochondrial redox status and Ca2+ homeostasis. A total of 80 market-age Arbor Acres male broiler chickens were sampled and categorized into control (CON) and WB groups based on the evaluation of myopathic lesions. PM muscle samples were collected (n = 8 in each group) for histopathological evaluation and biochemical analyses. Ultrastructural examination and histopathological changes suggested the occurrence of PM muscle damage in broiler chickens with WB myopathy. The WB group showed an increased level of reactive oxygen species and enhanced antioxidant capacities in mitochondria of PM muscle. These changes were related to impaired mitochondria morphology and mitochondrial dysfunction. In addition, abnormal expressions of Ca2+ channels led to substantial Ca2+ loss in SR and cytoplasmic Ca2+ overload, as well as Ca2+ accumulation in mitochondria, resulting in Ca2+ dyshomeostasis in PM muscle of broiler chickens with WB myopathy. Combined, these findings indicate that WB myopathy is related to mitochondrial dysfunction, mitochondrial redox status imbalance and Ca2+ dyshomeostasis, leading to WB-affected PM muscle damage.

For the hydraulic drilling tool under deep water, an integrated structure of a water hydraulic electrohydraulic motor is proposed, which consists of three parts: pump unit, motor unit, and DC brushless motor. The two-dimensional piston in the pump unit has two degrees of freedom of motion: rotation and reciprocation, so it is compact and can be matched with a high-speed motor to become a high-speed motor pump; the two sets of plungers in the motor unit are balanced with two end-facing cam drive mechanisms to achieve axial force, which is also suitable for high-speed rotation. In this paper, the mechanical structure and working principle of the electrohydraulic motor are described, the mathematical model of the output characteristics of the electrohydraulic motor is established, and the joint simulation model of Adams and AMESim is built, then the relationship between the dynamic characteristics of the electrohydraulic motor and the structure and working parameters is studied. The results show that the higher the speed of the pump unit, the smoother the characteristics of the electrohydraulic motor, when the motor speed is increased from 1000 r/min to 3000 r/min, the pulsation amplitude of the electrohydraulic motor speed is decreased by 200%; the plunger sub of the motor unit should take proper clearance, if the plunger sub clearance is increased to $12~\mu \text{m}$ , the output speed is decreased by 40% and the leakage volume is increased by 25 times; the motor unit should have proper back pressure to facilitate the smoothness and life of the motor, when the back pressure value is increased from 0.2 MPa to 1.2 MPa, the pressure pulsation at the beginning of the start-up is also greatly reduced.

Cellulose is a potential alternative to petroleum-derived polymers, and cellulose membranes are used in many applications such as sensors, flexible materials, and functional membranes. Most bottom-up methods are energy-, chemical-, and time-intensive compared to top-down methods for preparing cellulose membranes. Additionally, most methods to improve the hydrophobicity of cellulose membranes to increase their lifetime are complex and require large amounts of organic solvents. To balance sustainability, degradability, and service life from a whole life cycle perspective, which is the biggest challenge for the industrialization of cellulose membranes, a top-down approach was used here to prepare cellulose membranes using camphor pine, walnut, and loofah materials. The effect of low temperature heat treatment on the prepared membranes’ wettability and water stability were investigated. The results showed that the water stability of loofah cellulose membrane was influenced by both surface and internal wettability due to the non-homogeneous structure. The heat treatment temperature of 200 °C for loofah cellulose membrane, 150 °C for camphor pine cellulose membrane, and 225 °C for walnut cellulose membrane was more effective.

Silylation is an effective means of cellulose modification. However, the condensation reaction process between the hydrolysis products of the silane coupling agent and cellulose, as well as the structure of the coating, which both have a strong influence on the wettability, are still controversial. In this paper, the reactions of different methyltriethoxysilane hydrolysis products with cellulose were simulated via the density functional theory method. The reaction activity centers of the different methyltriethoxysilane hydrolysis products in an ethanol solution were analyzed via the front-line orbital theory and the Fukui function. The silylation reaction of different methyltriethoxysilane hydrolysis products in an ethanol solution on the cellulose surface were investigated via the transition state theory. The results show that although the initial hydrolysis product has the lowest grafting energy barrier, considering the whole process of grafting and condensation on the cellulose surface, the hydrolysis product with two hydroxyl groups is more favorable for the growth of organosilicon on the cellulose surface, so it is desirable to control the reaction where this product is dominant. In addition, the silylation process on the cellulose surface is more inclined to a multilayer coating mechanism.

It is critical for power system to uphold operation security while considering the cooperation of thermal power and new flexible resources, such as energy storage and demand response (DR). This paper investigates the integration of carbon emission trading with peak-load regulation trading to analyze the effects of carbon change generated using thermal power, energy storage, and demand response, and builds a deterministic multisource low-carbon peak-load regulation trading optimization model. To describe wind power uncertainty, we apply information gap decision theory (IGDT) to quantify the information gap between the predicted and actual data of wind power; subsequently, we construct a multisource low-carbon peak-load regulation trading optimization model based on IGDT considering the uncertainty. Finally, a local power grid in Northwest China is considered as a case study, and we establish regular, low-carbon, stochastic and comprehensive four peak-load regulation scenarios to analyze the impact of carbon emissions trading, energy storage, and DR involved in wind power peak-load regulation trading. The results show the following. (1) The individual application of the energy storage system (ESS) and DR can reduce peak-load regulation cost by 4.64% and 7.68%, respectively, whereas a 8.38% reduction is achieved when they are applied together. (2) When considering the uncertainty of wind power, the grid connected power of wind power is reduced by 2.15% and the total peak shaving cost is increased by 10%. With the increase in uncertainty, the cost of peak shaving trading scheme is always lower than the expected value, indicating that the IGDT method is effective. (3) When the price of the carbon emission trading ranges from 85–95 CN¥/t, the peak-load regulation cost of thermal power units are compensated; moreover, the peak-load regulation cost of wind power and allowable uncertainty reach optimum values when the acceptable price is less than 80 CN¥/t in the worst scenario. In summary, the ESS and DR can enhance the flexibility of the system for peak-load regulation, thus increasing wind power grid connection, and carbon emissions trading can improve the net economy of peak-load regulation of thermal power units. The IGDT method can describe the uncertainty risk of wind power output and establish a peak-load regulation trading scheme that satisfies the expectations of decision makers with different risk attitudes. The peak-load regulation trading scheme must carefully consider the carbon emission trading price: if the carbon emission trading price is excessively high, it will result in a retaliatory grid connection of wind power to compensate for the carbon trading costs, and the system cost will increase rapidly.

Objective This work was conducted to investigate the effects of oxidative stress on meat quality, mitochondrial function, calcium metabolism and ferroptosis of broilers. Methods In this study, a total of 144 one-day-old male Ross 308 chicks were divided into 3 groups (control group, saline group, and hydrogen peroxide [H2O2] group) with 6 replicates of 8 broilers each. The study lasted for 42 d. The broilers in the saline and H2O2 groups were intraperitoneally injected with 0.75% saline and 10.0% H2O2 on the 16th and 37th day of the experimental period respectively, the injection volumes were 1.0 mL/kg of broiler body weight. On the 42nd day of the experimental period, two chicks were randomly selected from each cage, a total of thirty-six chicks were stunned by electric shock and slaughtered to collect breast muscle samples. Results The H2O2 exposure reduced pH value, increased drip loss and shear force of breast meat (p

Abstract Background Chronic heat stress has a negative impact on poultry meat quality. Although this has been extensively investigated, previous studies have primarily focused on metabolic alterations and oxidative stress in the pectoralis major (PM) muscle under chronic heat stress, and not all of the underlying molecular mechanisms are completely understood. Methods A total of 144 male Arbor Acres broilers (28 d old) were randomly allocated into 3 treatment groups: (1) the normal control (NC) group, with broilers raised at 22 °C and fed a basal diet; (2) the heat stress (HS) group, with birds raised at 32 °C and fed a basal diet; and (3) the pair-fed (PF) group, with birds raised at 22 °C and fed the amount of feed equal to the feed consumed on the previous day by the HS group. The experiment lasted for 14 d. Results Chronic heat stress decreased the average daily feed intake and average daily gain, increased feed:gain ratio (P

ABSTRACT: Approaches for the diagnosis of wooden breast (WB) myopathy in live birds are urgently required before applying intervention strategies to reduce occurrence and severity for the poultry industry. The objective of this study was to characterize the serum metabolic profiles in male broilers affected by WB and to identify biomarkers related to this myopathy. Broilers were categorized into normal (CON) and WB groups based on gross scoring and histological evaluation. Gas chromatography-mass spectrometry-based metabolomics, multivariate analysis, and orthogonal partial least squares discriminant analysis revealed a clear separation between CON and WB. A total of 73 significantly different (P < 0.05) metabolites with 17 upregulated and 56 downregulated were identified, which were mainly involved in pathways of alanine, aspartate, and glutamate metabolism, carbohydrate metabolism, and taurine and hypotaurine metabolism. By using the nested cross-validation function of random forest analysis, 9 significantly altered (P < 0.05) metabolites (cerotinic acid, arabitol, phosphoenolpyruvate, terephthalic acid, cis-gondoic acid, N-acetyl-d-glucosamine, 4-hydroxymandelic acid, caffeine, and xanthurenic acid) were identified as biomarkers with an excellent discriminant performance for WB myopathy. Collectively, this study provides new insights for a deeper understanding of the pathogenesis and provides metabolites as biomarkers for diagnostic utilization of WB myopathy.

This study aimed to investigate the effect of wooden breast (WB) myopathy on chemical composition, meat quality attributes and physiochemical characteristics of intramuscular connective tissue (IMCT) of broiler pectoralis major (PM) muscle. Thirty-six fillets were classified into varying degrees of WB condition, including normal, moderate and severe. Results show that WB myopathy altered the collagen profile in PM muscle by increasing total collagen content and decreasing collagen solubility. The composition of macromolecules in IMCT, including hydroxylysyl pyridoxine cross-linking, decorin and glycosaminoglycans, were increased with the severity of WB myopathy. Differential scanning calorimetry analysis indicated higher denaturation temperatures and lower denaturation enthalpy of IMCT for WB. Secondary structures of α-helix and β-sheet in the IMCT of WB were changed to β-turn and random coil. In addition, chemical composition and meat quality attributes showed a correlation with collagen profile and IMCT characteristics. Overall, this study emphasizes the effect of WB myopathy on IMCT and their contributions to meat quality variation.

Abstract Background Myelodysplastic syndromes (MDS) are a group of heterogeneous myeloid clonal disorders characterized by ineffective haematopoiesis and immune deregulation. Emerging evidence has shown the effect of bone marrow (BM) endothelial progenitor cells (EPCs) in regulating haematopoiesis and immune balance. However, the number and functions of BM EPCs in patients with different stages of MDS remain largely unknown. Methods Patients with MDS (N = 30), de novo acute myeloid leukaemia (AML) (N = 15), and healthy donors (HDs) (N = 15) were enrolled. MDS patients were divided into lower-risk MDS (N = 15) and higher-risk MDS (N = 15) groups according to the dichotomization of the Revised International Prognostic Scoring System. Flow cytometry was performed to analyse the number of BM EPCs. Tube formation and migration assays were performed to evaluate the functions of BM EPCs. In order to assess the gene expression profiles of BM EPCs, RNA sequencing (RNA-seq) were performed. BM EPC supporting abilities of haematopoietic stem cells (HSCs), leukaemia cells and T cells were assessed by in vitro coculture experiments. Results Increased but dysfunctional BM EPCs were found in MDS patients compared with HDs, especially in patients with higher-risk MDS. RNA-seq indicated the progressive change and differences of haematopoiesis- and immune-related pathways and genes in MDS BM EPCs. In vitro coculture experiments verified that BM EPCs from HDs, lower-risk MDS, and higher-risk MDS to AML exhibited a progressively decreased ability to support HSCs, manifested as elevated apoptosis rates and intracellular reactive oxygen species (ROS) levels and decreased colony-forming unit plating efficiencies of HSCs. Moreover, BM EPCs from higher-risk MDS patients demonstrated an increased ability to support leukaemia cells, characterized by increased proliferation, leukaemia colony-forming unit plating efficiencies, decreased apoptosis rates and apoptosis-related genes. Furthermore, BM EPCs induced T cell differentiation towards more immune-tolerant cells in higher-risk MDS patients in vitro. In addition, the levels of intracellular ROS and the apoptosis ratios were increased in BM EPCs from MDS patients, especially in higher-risk MDS patients, which may be therapeutic candidates for MDS patients. Conclusion Our results suggest that dysfunctional BM EPCs are involved in MDS patients, which indicates that improving haematopoiesis supporting ability and immuneregulation ability of BM EPCs may represent a promising therapeutic approach for MDS patients.

This study aimed to investigate the effects of dietary corn-resistant starch on the bile acid metabolism of broilers. In total, 80, 1-day-old male broilers were randomly distributed into two groups fed either the basic normal corn–soybean diet or a diet supplemented with 40 g/kg of corn-resistant starch. The results showed that dietary supplementation of 4% corn-resistant starch increased the F/G during the periods from 21 to 42 d. Resistant starch supplementation reduced the lipid levels in plasma, and the contents of total bile acids were increased with the altered bile acid profile in the ileum. A diet with corn resistant starch decreased the enzyme contents of the classical pathway of bile acid synthesis and activated the signaling pathway of FXR/LRH-1 in the liver. A decreased abundance of Clostridium cluster XIVa was found in the ileal digesta of the resistant starch group, and its abundance was negatively correlated with the level of lithocholic acid. In summary, the RS was effective at reducing broiler plasma and liver lipid levels, which was probably due to the change in bile acid synthesis and reabsorption capacities. These findings provided a unique landscape of the relationship between bile acid metabolism and resistant starch in broilers.

The dropper through bends and bears dynamic impact load before and after the train passes in actual service, which has an important impact on the fatigue life of the dropper. In this paper, a simulation model which can simulate the interaction between pantograph and catenary is established by using the numerical simulation method. A dropper model which can simulate the dynamic stress of the dropper is established through the beam-link combination element. The simulation result shows that among the six droppers in a span, the dynamic force of No. 1 and No. 6 droppers is the smallest, and the dynamic force of No. 3 and No. 4 droppers is the largest. The dynamic load variation characteristics of the dropper are characterized by the dynamic coefficient. When the front and rear pantograph pass through, the maximum dynamic force of the dropper appears when the rear pantograph passes through. The maximum dynamic force is located in the middle of the dropper. Through the research of this paper, the simulation method of catenary and dropper is established, and the dynamic stress process of dropper is analyzed, which lays a technical foundation for the subsequent research on the fatigue failure mechanism of dropper.

ABSTRACT: Liver is a central metabolic organ, which is sensitive to heat stress. Liver damage affects animals' health and endangers the livestock and poultry industry. This study aimed to investigate the mechanism of chronic heat stress-induced liver damage in broiler chickens. Broilers were divided into 3 treatments: normal control group (NOR, 22°C), heat stress group (HS, 32°C) and pair-feeding group (PF, 22°C) for a 7-d and 14-d trial. The results showed that 7 d heat exposure caused microvesicular steatosis and reduced glutamine synthetase activity in broiler liver (P < 0.05). After 14 d of heat exposure, heat stress caused vacuolar degeneration and apoptosis in the liver; elevated liver relative weight and liver glutaminase activity as well as plasma ammonia level (P < 0.05). Additionally, heat stress enhanced GRP78 protein expression and the mRNA expressions of endoplasmic reticulum (ER) stress responses genes and apoptosis-related genes in broiler liver after 14 d of heat exposure (P < 0.05). In conclusion, chronic heat stress triggered ER stress-induced apoptosis and caused liver damage, which may compromise ammonia detoxification in broiler liver.

Abstract Dysfunctional megakaryopoiesis hampers platelet production, which is closely associated with thrombocytopenia (PT). Macrophages (MФs) are crucial cellular components in the bone marrow (BM) microenvironment. However, the specific effects of M1 MФs or M2 MФs on regulating megakaryocytes (MKs) are largely unknown. In the current study, aberrant BM-M1/M2 MФ polarization, characterized by increased M1 MФs and decreased M2 MФs and accompanied by impaired megakaryopoiesis-supporting abilities, was found in patients with PT post-allotransplant. RNA-seq and western blot analysis showed that the PI3K-AKT pathway was downregulated in the BM MФs of PT patients. Moreover, in vitro treatment with PI3K-AKT activators restored the impaired megakaryopoiesis-supporting ability of MФs from PT patients. Furthermore, we found M1 MФs suppress, whereas M2 MФs support MK maturation and platelet formation in humans. Chemical inhibition of PI3K-AKT pathway reduced megakaryopoiesis-supporting ability of M2 MФs, as indicated by decreased MK count, colony-forming unit number, high-ploidy distribution, and platelet count. Importantly, genetic knockdown of the PI3K-AKT pathway impaired the megakaryopoiesis-supporting ability of MФs both in vitro and in a MФ-specific PI3K-knockdown murine model, indicating a critical role of PI3K-AKT pathway in regulating the megakaryopoiesis-supporting ability of M2 MФs. Furthermore, our preliminary data indicated that TGF-β released by M2 MФs may facilitate megakaryopoiesis through upregulation of the JAK2/STAT5 and MAPK/ERK pathways in MKs. Taken together, our data reveal that M1 and M2 MФs have opposing effects on MKs in a PI3K-AKT pathway-dependent manner, which may lead to new insights into the pathogenesis of thrombocytopenia and provide a potential therapeutic strategy to promote megakaryopoiesis.

Objective Wooden breast (WB) is a novel myopathy affecting modern broiler chickens, which causes substantial economic losses in the poultry industry. The objective of this study was to evaluate the effect of WB abnormality on meat quality, redox status, as well as the expression of genes of the nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway. Methods A total of 80 broilers (Ross 308, 42 days of age, about 2.6 kg body weight) raised at Jiujin farm (Suqian, Jiangsu, China) were used. Twelve unaffected (no detectable hardness of the breast area) and twelve WB-affected (diffuse remarkable hardness in the breast muscle) birds were selected from the commercial broiler farm according to the criteria proposed by previous studies. Results The results indicated that WB showed histological lesions characterized by fiber degeneration and fibrosis, along with an increase of muscle fiber diameter (p

This article presents the design of a two-dimensional (2D) piston pump flow-distribution port with an overlapped structure that reduces backflow in the pump chamber and pressure ripples at the pump outlet, thus minimizing vibration and noise caused by the high-frequency distribution process of a single two-dimensional (2D) piston pump. We describe the flow distribution structure and operation principle of the 2D pump, create a mathematical model of the pump chamber pressure by using the motion and flow continuity equations of the 2D piston, and use a Matlab program to compile and solve them. The influence of the flow distribution port overlap on the pump chamber pressure and the outlet flow rate was simulated. A prototype was designed and tested on a dynamic performance test bench. Our test bench results show that the flow distribution port overlap can reduce the pressure ripple at the pump outlet, which is consistent with the simulation results.

Ge-Sb-Te compounds (GST), the well-known phase-change materials, are considered to be promising thermoelectric (TE) materials due to their decent thermoelectric performance. While Ge2Sb2Te5 and GeSb2Te4 have been extensively studied, the TE performance of GeSb4Te7 has not been well explored. Reducing the excessive carrier concentration is crucial to improving TE performance for GeSb4Te7. In this work, we synthesize a series of Se-alloyed GeSb4Te7 compounds and systematically investigate their structures and transport properties. Raman analysis reveals that Se alloying introduces a new vibrational mode of GeSe2, enhancing the interatomic interaction forces within the layers and leading to the reduction of carrier concentration. Additionally, Se alloying also increases the effective mass and thus improves the Seebeck coefficient of GeSb4Te7. The decrease in carrier concentration reduces the carrier thermal conductivity, depressing the total thermal conductivity. Finally, a maximum zT value of 0.77 and an average zT value of 0.48 (300–750 K) have been obtained in GeSb4Te5.5Se1.5. This work investigates the Raman vibration modes and the TE performance in Se-alloyed GeSb4Te7 sheddinglight on the performance optimization of other GST materials.

Oxidative stress has always been a hot topic in poultry science. However, studies concerning the effects of redox status and glucose metabolism induced by hydrogen peroxide (H2O2) in the breast muscle of broilers have been rarely reported. This study was aimed to evaluate the impact of intraperitoneal injection of H2O2 on oxidative damage and glycolysis metabolism of breast muscle in broilers. We also explored the activation of the nuclear factor erythroid 2–related factor 2 (Nrf2) signaling pathway to provide possible mechanism of the redox imbalance. Briefly, a total of 320 one-day-old Arbor Acres chicks were randomly divided into 5 treatments with 8 replicates of 8 birds each (noninjected control, 0.75% saline-injected, 2.5, 5.0, and 10.0% H2O2-injected treatments). Saline group was intraperitoneally injected with physiological saline (0.75%) and H2O2 groups received an intraperitoneal injection of H2O2. The dosage of the injection was 1.0 mL/kg BW. All birds in the saline and H2O2 groups were injected on days 16 and 37 of the experimental period. At 42 d of age, 40 birds (8 cages per group and one chicken per cage) were selected to be stunned electrically (50 V, alternating current, 400 Hz for 5 s each one), and then immediately slaughtered via exsanguination. The results showed that broilers in the H2O2 injection group linearly exhibited higher contents of reactive oxygen species, carbonyl and malondialdehyde, and lower total antioxidant capacity and glutathione peroxidase activities. With the content of H2O2 increased, the H2O2 groups linearly downregulated the mRNA expressions of GPX, CAT, HMOX1, NQO1, and Nrf2 and its downstream target genes. In addition, H2O2 increased serum activities of creatine kinase and lactate dehydrogenase. Meanwhile, in the pectoral muscle, the glycogen content was linearly decreased, and the lactate content was linearly increased in muscle of broilers injected with H2O2. In addition, the activities of glycolytic enzymes including pyruvate kinase, hexokinase, and lactate dehydrogenase were linearly increased after exposure to H2O2. In conclusion, H2O2 injection could impair antioxidant status and enhance anaerobic metabolism of breast muscle in broilers.

Heat stress impairs growth performance and alters body protein and amino acid metabolism. This study was investigated to explore how body protein and amino acid metabolism changed under heat stress (HS) and the stress adaptation mechanism. A total of 144 broilers (28 d old) were divided into 3 treatment groups for 1 wk: HS group (32°C), normal control group (22°C), and pair-feeding group (22°C). We found that HS elevated the feed-to-gain ratio, reduced the ADFI and ADG, decreased breast muscle mass and plasma levels of several amino acids (glycine, lysine, threonine, and tyrosine), and increased serum glutamic oxaloacetic transaminase (GOT) activity and corticosterone (CORT) level and liver GOT and glutamic pyruvic transaminase activities. Heat stress elevated muscle atrophy F-box mRNA expression and reduced mRNA expression of the 70-kD ribosomal protein S6 kinase in the breast muscle of broilers. Broilers in the HS group exhibited striking increases of mRNA expressions of solute carrier family 1 member 1, family 3 member 1, family 7 member 1, and family 7 member-like in the liver and liver gluconeogenesis genes (PCKc, PCKm, PC, and FBP1) in comparison with the other 2 groups. In conclusion, HS increased the circulating CORT level and subsequently caused muscle protein breakdown to provide amino acid substrates to liver gluconeogenesis responsible for energy supply.

Objective This study was conducted to investigate the effects of dietary corn resistant starch (RS) on the intestinal morphology and barrier functions of broilers. Methods A total of 320 one-day-old broilers were randomly allocated to 5 dietary treatments: one normal corn–soybean (NC) diet, one corn–soybean–based diet supplementation with 20% corn starch (CS), and 3 corn–soybean–based diets supplementation with 4%, 8%, and 12% corn resistant starch (RS) (identified as 4% RS, 8% RS, and 12% RS, respectively). Each group had eight replicates with eight broilers per replicate. After 21 days feeding, one bird with a body weight (BW) close to the average BW of their replicate was selected and slaughtered. The samples of duodenum, jejunum, ileum, caecum digesta, and blood were collected. Results Birds fed 4% RS, 8% RS and 12% RS diets showed lower feed intake, BW gain, jejunal villus height (VH), duodenal crypt depth (CD), jejunal VH/CD ratio, duodenal goblet cell density as well as mucin1 mRNA expressions compared to the NC group, but showed higher concentrations of cecal acetic acid and butyric acid, percentage of jejunal proliferating cell nuclear antigen-positive cells and delta like canonical Notch ligand 4 (Dll4), and hes family bHLH transcription factor 1 mRNA expressions. However, there were no differences on the plasma diamine oxidase activity and D-lactic acid concentration among all groups. Conclusion These findings suggested that RS could suppress intestinal morphology and barrier functions by activating Notch pathway and inhibiting the development of goblet cells, resulting in decreased mucins and tight junction mRNA expression.

Bone marrow (BM) endothelial progenitor cell (EPC) damage of unknown mechanism delays the repair of endothelial cells (EC) and recovery of hematopoiesis after chemo-radiotherapy. We found increased levels of the glycolytic enzyme PFKFB3 in the damaged BM EPC of patients with poor graft function, a clinical model of EPC damage-associated poor hematopoiesis after allogeneic hematopoietic stem cell transplantation. Moreover, in vitro the glycolysis inhibitor 3-(3-pyridinyl)- 1-(4-pyridinyl)-2-propen-1-one (3PO) alleviated the damaged BM EPC from patients with poor graft function. Consistently, PFKFB3 overexpression triggered BM EPC damage after 5-fluorouracil treatment and impaired hematopoiesis-supporting ability in vitro. Mechanistically, PFKFB3 facilitated pro-apoptotic transcription factor FOXO3A and expression of its downstream genes, including p21, p27, and FAS, after 5-fluorouracil treatment in vitro. Moreover, PFKFB3 induced activation of NF-κB and expression of its downstream adhesion molecule E-selectin, while it reduced hematopoietic factor SDF-1 expression, which could be rescued by FOXO3A silencing. High expression of PFKFB3 was found in damaged BM EC of murine models of chemo-radiotherapy-induced myelosuppression. Furthermore, a murine model of BM EC-specific PFKFB3 overexpression demonstrated that PFKFB3 aggravated BM EC damage, and impaired the recovery of hematopoiesis after chemotherapy in vivo, effects which could be mitigated by 3PO, indicating a critical role of PFKFB3 in regulating BM EC damage. Clinically, PFKFB3-induced FOXO3A expression and NF-κB activation were confirmed to contribute to the damaged BM EPC of patients with acute leukemia after chemotherapy. 3PO repaired the damaged BM EPC by reducing FOXO3A expression and phospho-NF-κB p65 in patients after chemotherapy. In summary, our results reveal a critical role of PFKFB3 in triggering BM EPC damage and indicate that endothelial-PFKFB3 may be a potential therapeutic target for myelosuppressive injury.

ABSTRACT: Oxidative stress is common in the whole process of broiler production, and breast muscle is one of the target organs most vulnerable to oxidative attack. When broilers are subjected to oxidative stress, the regulation of adenosine 5-monophosphate activated protein kinase (AMPK) is a critical path to maintain the dynamic balance of intracellular energy. However, whether calcium/calmodulin-dependent protein kinase (CaMKK) and liver kinase B1 (LKB1) are involved in the regulation of AMPK activation in broiler breast muscle under oxidative stress has not been elucidated. In this study, a total of 144 one-day-old male Ross 308 chicks were selected, with an average body weight of 43.44 ± 0.04 g. The broilers were divided into 3 groups with 6 replicates of 8 broilers each (control group, intraperitoneal injection of physiological saline group, and intraperitoneal injection of hydrogen peroxide [H2O2] group), the injection time was selected on the 16th and 37th day of the experimental period, the injection volumes were 1.0 mL/kg broiler body weight. The results of this experiment showed that H2O2 exposure reduced the average daily gain (ADG) and increased the feed to gain ratio (F/G), the level of corticosterone (CORT) and the activity of lactate dehydrogenase (LDH) in serum were increased after H2O2 exposure. H2O2 exposure also increased the contents of reactive oxygen species (ROS) and protein carbonyl, but decreased the activities of catalase (CAT), total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) in breast muscle. After H2O2 exposure, the activity of pyruvate dehydrogenase (PDH) was decreased, the content of glycogen was reduced, and the contents of adenosine monophosphate (AMP) and lactate were increased in breast muscle. In addition, H2O2 exposure increased the content of Ca2+, upregulated the protein expression levels of CaMKK1 and p-AMPK, and increased the activities of hexokinase (HK) and LDH in breast muscle. These findings suggested that the activation of CaMKK/LKB1/AMPK signaling pathway would be associated with the accelerated glycolysis of broiler breast muscle under oxidative stress.

This study investigated the effects of dietary corn-resistant starch on lipid metabolism of broilers and its potential relationship with cecal microbiota modulation. A total of three hundred twenty 1-day-old male broilers were randomly assigned into 5 dietary treatments: 1 normal corn–soybean (NC) diet, 1 corn–soybean–based diet supplementation with 20% corn starch (CS), and 3 corn–soybean–based diets supplementation with 4, 8, and 12% corn resistant starch (RS) (identified as 4%RS, 8%RS, and 12%RS, respectively). Each group had 8 replicates with 8 broilers per replicate. The experiment lasted 21 d. The results showed that the abdominal fat percentage were lower in birds from 8%RS and 12%RS groups (0.75 and 0.58%, respectively) than those from NC and CS groups (1.20 and 1.28%, respectively; P

Heat stress is a broiler welfare issue and economic deficit to the broiler industry. Water atomizing with three-dimensional forced ventilation, a holding treatment after summer transport for broiler, has been proved to significantly improve water holding capacity of fresh meat. However, effectiveness of this treatment on water retention after freeze-thaw needs to be conducted. Therefore, the objective of this study was to assess whether water atomizing with forced ventilation could increase freeze-thaw meat quality after birds slaughtering. Arbor Acres broiler (n = 105), undergoing 32°C ambient temperature transport, was randomly categorized into 3 treatments: 1) T group, which underwent 45-min transport without rest; 2) TR group, which underwent 45-min transport with 1-h rest; and the 3) TWFR group, which underwent 45-min transport followed by 15-min water atomizing with three-dimensional forced ventilation and 45-min rest. All birds were hot-deboned within 30-min postmortem. A total of 105 breast fillets were collected and split into halves, which left part fillets were kept in 4°C and for meat analysis, the other part fillets, marked with T-F, TR-F, and TWFR-F, were frozen (−18°C) for 1 mo and then thawed overnight for meat quality analysis. Regardless of fresh or frozen treatment among 3 groups, TWFR has the highest pH which was more than 6.01 (P