Hypoxia-mediated programmed cell death is involved in the formation of wooden breast in broilers

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<0.01)was found along with pathological structure damage of myofibers in the WB group.The number of capillaries per fiber in PM muscle,and the levels of p O_(2) and s O_(2) in the blood,were significantly decreased(P<0.01),while the levels of p CO_(2) and TCO_(2) in the blood were significantly increased(P<0.05),suggesting hypoxic conditions in the PM muscle of the WB group.We further evaluated the PCD-related pathways including autophagy,apoptosis,and necroptosis to understand the consequence response to enhanced hypoxic conditions in the PM muscle of birds with WB.The ratio of LC3 II to LC3 I,and the autophagy-related factors HIF-1α,BNIP3,Beclin1,AMPKα,and ULK1 at the m RNA and protein levels,were all significantly upregulated(P<0.05),showing that autophagy occurred in the PM muscle of the WB group.The apoptotic index,as well as the expressions of Bax,Cytc,caspase 9,and caspase 3,were significantly increased(P<0.05),whereas Bcl-2 was significantly decreased(P<0.05)in the WB-affected PM muscle,indicating the occurrence of apoptosis mediated by the mitochondrial pathway.Additionally,the expressions of necroptosis-related factors RIP1,RIP3,and MLKL,as well as NF-κB and the pro-inflammatory cytokines TNF-α,IL-1β,and IL-6,were all significantly enhanced(P<0.05)in the WB-affected PM muscle.Conclusions The WB myopathy reduces blood supply and induces hypoxia in the PM muscle,which is closely related to the occurrence of PCD including apoptosis,autophagy,and necroptosis within myofibers,and finally leads to abnormal muscle damage and the development of WB in broilers.

The correlation between gut microbiome and atrial fibrillation: pathophysiology and therapeutic perspectives

Regulation of gut microbiota and its impact on human health is the theme of intensive research.The incidence and prevalence of atrial fibrillation(AF)are continuously escalating as the global population ages and chronic disease survival rates increase;however,the mechanisms are not entirely clarified.It is gaining awareness that alterations in the assembly,structure,and dynamics of gut microbiota are intimately engaged in the AF progression.Owing to advancements in next-generation sequencing technologies and computational strategies,researchers can explore novel linkages with the genomes,transcriptomes,proteomes,and metabolomes through parallel meta-omics approaches,rendering a panoramic view of the culture-independent microbial investigation.In this review,we summarized the evidence for a bidirectional correlation between AF and the gut microbiome.Furthermore,we proposed the concept of“gut-immune-heart”axis and addressed the direct and indirect causal roots between the gut microbiome and AF.The intricate relationship was unveiled to generate innovative microbiota-based preventive and therapeutic interventions,which shed light on a definite direction for future experiments.

The microbial community,nutrient supply and crop yields differ along a potassium fertilizer gradient under wheat-maize double-cropping systems

Soil microorganisms play critical roles in ecosystem function.However,the relative impact of the potassium(K)fertilizer gradient on the microbial community in wheat-maize double-cropping systems remains unclear.In this long-term field experiment(2008-2019),we researched bacterial and fungal diversity,composition,and community assemblage in the soil along a K fertilizer gradient in the wheat season(K0,no K fertilizer;K1,45 kg ha^(-1) K_(2)O;K_(2),90 kg ha^(-1)K_(2)O;K3,135 kg ha^(-1)K_(2)O)and in the maize season(K0,no K fertilizer;K_(1),150 kg ha^(-1) K_(2)O;K_(2),300 kg ha^(-1)K_(2)O;K_(3),450 kg ha^(-1)K_(2)O)using bacterial 16S rRNA and fungal internally transcribed spacer(ITS)data.We observed that environmental variables,such as mean annual soil temperature(MAT)and precipitation,available K,ammonium,nitrate,and organic matter,impacted the soil bacterial and fungal communities,and their impacts varied with fertilizer treatments and crop species.Furthermore,the relative abundance of bacteria involved in soil nutrient transformation(phylum Actinobacteria and class Alphaproteobacteria)in the wheat season was significantly increased compared to the maize season,and the optimal K fertilizer dosage(K2 treatment)boosted the relative bacterial abundance of soil nutrient transformation(genus Lactobacillus)and soil denitrification(phylum Proteobacteria)bacteria in the wheat season.The abundance of the soil bacterial community promoting root growth and nutrient absorption(genus Herbaspirillum)in the maize season was improved compared to the wheat season,and the K2 treatment enhanced the bacterial abundance of soil nutrient transformation(genus MND1)and soil nitrogen cycling(genus Nitrospira)genera in the maize season.The results indicated that the bacterial and fungal communities in the double-cropping system exhibited variable sensitivities and assembly mechanisms along a K fertilizer gradient,and microhabitats explained the largest amount of the variation in crop yields,and improved wheat?maize yields by 11.2-22.6 and 9.2-23.8%with K addition,respectively.These modes are shaped contemporaneously by the different meteorological factors and soil nutrient changes in the K fertilizer gradients.

北京2022年冬奥会六足冰壶机器人机构设计与运动规划

When a curling rock slides on an ice sheet with an initial rotation,a lateral movement occurs,which is known as the curling phenomenon.The force of friction between the curling rock and the ice sheet changes continually with changes in the environment;thus,the sport of curling requires great skill and experience.The throwing of the curling rock is a great challenge in robot design and control,and existing curling robots usually adopt a combination scheme of a wheel chassis and gripper that differs significantly from human throwing movements.A hexapod curling robot that imitates human kicking,sliding,pushing,and curling rock rotating was designed and manufactured by our group,and completed a perfect show during the Beijing 2022 Winter Olympics Games.Smooth switching between the walking and throwing tasks is realized by the robot’s morphology transformation based on leg configuration switching.The robot’s controlling parameters,which include the kicking velocity v_(k),pushing velocity v_(p),orientation angle θc,and rotation velocityω,are determined by aiming and sliding models according to the estimated equivalent friction coefficientμ_(equ)and ratio e of the front and back frictions.The stable errors between the target and actual stopping points converge to 0.2 and 1.105 m in the simulations and experiments,respectively,and the error shown in the experiments is close to that of a well-trained wheelchair curling athlete.This robot holds promise for helping ice-makers rectify ice sheet friction or assisting in athlete training.

Hydrogen sulfide responsive nanoplatforms: Novel gas responsive drug delivery carriers for biomedical applications

Hydrogen sulfide(H_(2)S)is a toxic,essential gas used in various biological and physical processes and has been the subject of many targeted studies on its role as a new gas transmitter.These studies have mainly focused on the production and pharmacological side effects caused by H_(2)S.Therefore,effective strategies to remove H_(2)S has become a key research topic.Furthermore,the development of novel nanoplatforms has provided new tools for the targeted removal of H_(2)S.This paper was performed to review the association between H_(2)S anddisease,relatedH_(2)S inhibitory drugs,aswell as H_(2)S responsive nanoplatforms(HRNs).This review first analyzed the role of H_(2)S in multiple tissues and conditions.Second,common drugs used to eliminate H_(2)S,as well as their potential for combination with anticancer agents,were summarized.Not only the existing studies on HRNs,but also the inhibition H_(2)S combined with different therapeutic methods were both sorted out in this review.Furthermore,this review provided in-depth analysis of the potential of HRNs about treatment or detection in detail.Finally,potential challenges of HRNs were proposed.This study demonstrates the excellent potential of HRNs for biomedical applications.

Multi-omics analyses provide insights into the evolutionary history and the synthesis of medicinal components of the Chinese wingnut

Chinese wingnut(Pterocarya stenoptera)is a medicinally and economically important tree species within the family Juglandaceae.However,the lack of high-quality reference genome has hindered its in-depth research.In this study,we successfully assembled its chromosome-level genome and performed multiomics analyses to address its evolutionary history and synthesis of medicinal components.A thorough examination of genomes has uncovered a significant expansion in the Lateral Organ Boundaries Domain gene family among the winged group in Juglandaceae.This notable increase may be attributed to their frequent exposure to flood-prone environments.After further differentiation between Chinese wingnut and Cyclocarya paliurus,significant positive selection occurred on the genes of NADH dehydrogenase related to mitochondrial aerobic respiration in Chinese wingnut,enhancing its ability to cope with waterlogging stress.Comparative genomic analysis revealed Chinese wingnut evolved more unique genes related to arginine synthesis,potentially endowing it with a higher capacity to purify nutrient-rich water bodies.Expansion of terpene synthase families enables the production of increased quantities of terpenoid volatiles,potentially serving as an evolved defense mechanism against herbivorous insects.Through combined transcriptomic and metabolomic analysis,we identified the candidate genes involved in the synthesis of terpenoid volatiles.Our study offers essential genetic resources for Chinese wingnut,unveiling its evolutionary history and identifying key genes linked to the production of terpenoid volatiles.

Smart Gait:A Gait Optimization Framework for Hexapod Robots

The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural mammals.This paper proposes a gait optimization framework for hexapod robots called Smart Gait.Smart Gait contains three modules:swing leg trajectory optimization,gait period&duty optimization,and gait sequence optimization.The full dynamics of a single leg,and the centroid dynamics of the overall robot are considered in the respective modules.The Smart Gait not only helps the robot to decrease the energy consumption when in locomotion,mostly,it enables the hexapod robot to determine its gait pattern transitions based on its current state,instead of repeating the formalistic clock-set step cycles.Our Smart Gait framework allows the hexapod robot to behave nimbly as a living animal when in 3D movements for the first time.The Smart Gait framework combines offline and online optimizations without any fussy data-driven training procedures,and it can run efficiently on board in real-time after deployment.Various experiments are carried out on the hexapod robot LittleStrong.The results show that the energy consumption is reduced by 15.9%when in locomotion.Adaptive gait patterns can be generated spontaneously both in regular and challenge environments,and when facing external interferences.

Efficient Monolithic Perovskite/Silicon Tandem Photovoltaics

Tunable bandgaps make halide perovskites promising candidates for developing tandem solar cells(TSCs),a strategy to break the radiative limit of 33.7%for single-junction solar cells.Combining perovskites with market-dominant crystalline silicon(c-Si)is particularly attractive;simple estimates based on the bandgap matching indicate that the efficiency limit in such tandem device is as high as 46%.However,state-of-the-art perovskite/c-Si TSCs only achieve an efficiency of~32.5%,implying significant challenges and also rich opportunities.In this review,we start with the operating mechanism and efficiency limit of TSCs,followed by systematical discussions on wide-bandgap perovskite front cells,interface selective contacts,and electrical interconnection layer,as well as photon management for highly efficient perovskite/c-Si TSCs.We highlight the challenges in this field and provide our understanding of future research directions toward highly efficient and stable large-scale wide-bandgap perovskite front cells for the commercialization of perovskite/c-Si TSCs.

Psychological Status and Warfarin Therapy in Patients after Valve Replacement during the COVID-19 Pandemic:A Cross-sectional Study

Objective The standardization of warfarin anticoagulant therapy is the key to lifelong treatment for patients after heart valve replacement.The present study explored the possible risk factors for anxiety and depression during the coronavirus disease 2019(COVID-19)pandemic and analyzed the influence of psychological state on medication safety.Methods Eligible patients received a web-based questionnaire survey via the Wenjuanxing platform during outpatient visits.Depression was evaluated by the Self-Rating Depression Scale(SDS).Anxiety was evaluated by the Self-Rating Anxiety Scale(SAS).Medication adherence was evaluated by the Morisky scale.Results A total of 309 patients(aged 52.2±11.4 years)were included in the present study.The SDS score of all included patients was 36.9±9.4 points,of which 11(3.6%)patients were diagnosed as having depression.The SAS score of all included patients was 43.1±9.3 points,of which 71(23%)patients were diagnosed as having anxiety.Seven patients(2.3%)had both anxiety and depression.Logistic regression analysis revealed that only monthly income was an independent influencing factor for depression.Regarding anxiety,patients who underwent repeated operations had a 2.264-fold greater risk,and patients who received combination medication had a 2.140-fold greater risk.More bleeding events and coagulation disorders could be observed in patients with anxiety,depression or both.When anxiety occurred,patients showed worse medication adherence.However,depression had no significant effect on medication adherence.Conclusion During the COVID-19 pandemic,the detection rate of mental illnesses such as anxiety and depression was high,which seriously affected the medication safety of warfarin.Analysis of its influencing factors will provide a reference for further standardized regulation of warfarin anticoagulant therapy after valve replacement.

Brain regulates weight bearing bone through PGE2 skeletal interoception: implication of ankle osteoarthritis and pain

Bone is a mechanosensitive tissue and undergoes constant remodeling to adapt to the mechanical loading environment.However,it is unclear whether the signals of bone cells in response to mechanical stress are processed and interpreted in the brain.In this study,we found that the hypothalamus of the brain regulates bone remodeling and structure by perceiving bone prostaglandin E2(PGE2)concentration in response to mechanical loading.Bone PGE2 levels are in proportion to their weight bearing.When weight bearing changes in the tail-suspension mice,the PGE2 concentrations in bones change in line with their weight bearing changes.Deletion of cyclooxygenase-2(COX2)in the osteoblast lineage cells or knockout of receptor 4(EP4)in sensory nerve blunts bone formation in response to mechanical loading.Moreover,knockout of TrkA in sensory nerve also significantly reduces mechanical load-induced bone formation.Moreover,mechanical loading induces cAMP-response element binding protein(CREB)phosphorylation in the hypothalamic arcuate nucleus(ARC)to inhibit sympathetic tyrosine hydroxylase(TH)expression in the paraventricular nucleus(PVN)for osteogenesis.Finally,we show that elevated PGE2 is associated with ankle osteoarthritis(AOA)and pain.Together,our data demonstrate that in response to mechanical loading,skeletal interoception occurs in the form of hypothalamic processing of PGE2-driven peripheral signaling to maintain physiologic bone homeostasis,while chronically elevated PGE2 can be sensed as pain during AOA and implication of potential treatment.

Identification of a novel inflammatory-related gene signature to evaluate the prognosis of gastric cancer patients

BACKGROUND Gastric cancer(GC)is a highly aggressive malignancy with a heterogeneous nature,which makes prognosis prediction and treatment determination difficult.Inflammation is now recognized as one of the hallmarks of cancer and plays an important role in the aetiology and continued growth of tumours.Inflammation also affects the prognosis of GC patients.Recent reports suggest that a number of inflammatory-related biomarkers are useful for predicting tumour prognosis.However,the importance of inflammatory-related biomarkers in predicting the prognosis of GC patients is still unclear.AIM To investigate inflammatory-related biomarkers in predicting the prognosis of GC patients.was constructed using the least absolute shrinkage and selection operator Cox regression model based on the GEO database.GC patients from the GSE26253 cohort were used for validation.Univariate and multivariate Cox analyses were used to determine the independent prognostic factors,and a prognostic nomogram was established.The calibration curve and the area under the curve based on receiver operating characteristic analysis were utilized to evaluate the predictive value of the nomogram.The decision curve analysis results were plotted to quantify and assess the clinical value of the nomogram.Gene set enrichment analysis was performed to explore the potential regulatory pathways involved.The relationship between tumour immune infiltration status and risk score was analysed via Tumour Immune Estimation Resource and CIBERSORT.Finally,we analysed the association between risk score and patient sensitivity to commonly used chemotherapy and targeted therapy agents.RESULTS A prognostic model consisting of three inflammatory-related genes(MRPS17,GUF1,and PDK4)was constructed.Independent prognostic analysis revealed that the risk score was a separate prognostic factor in GC patients.According to the risk score,GC patients were stratified into high-and low-risk groups,and patients in the high-risk group had significantly worse prognoses according to age,sex,TNM stage and Lauren type.Consensus clustering identified three subtypes of inflammation that could predict GC prognosis more accurately than traditional grading and staging.Finally,the study revealed that patients in the low-risk group were more sensitive to certain drugs than were those in the high-risk group,indicating a link between inflammation-related genes and drug sensitivity.CONCLUSION In conclusion,we established a novel three-gene prognostic signature that may be useful for predicting the prognosis and personalizing treatment decisions of GC patients.

The cardiovascular system at high altitude:A bibliometric and visualization analysis

BACKGROUND When exposed to high-altitude environments,the cardiovascular system undergoes various changes,the performance and mechanisms of which remain controversial.AIM To summarize the latest research advancements and hot research points in the cardiovascular system at high altitude by conducting a bibliometric and visualization analysis.METHODS The literature was systematically retrieved and filtered using the Web of Science Core Collection of Science Citation Index Expanded.A visualization analysis of the identified publications was conducted employing CiteSpace and VOSviewer.RESULTS A total of 1674 publications were included in the study,with an observed annual increase in the number of publications spanning from 1990 to 2022.The United States of America emerged as the predominant contributor,while Universidad Peruana Cayetano Heredia stood out as the institution with the highest publication output.Notably,Jean-Paul Richalet demonstrated the highest productivity among researchers focusing on the cardiovascular system at high altitude.Furthermore,Peter Bärtsch emerged as the author with the highest number of cited articles.Keyword analysis identified hypoxia,exercise,acclimatization,acute and chronic mountain sickness,pulmonary hypertension,metabolism,and echocardiography as the primary research hot research points and emerging directions in the study of the cardiovascular system at high altitude.CONCLUSION Over the past 32 years,research on the cardiovascular system in high-altitude regions has been steadily increasing.Future research in this field may focus on areas such as hypoxia adaptation,metabolism,and cardiopulmonary exercise.Strengthening interdisciplinary and multi-team collaborations will facilitate further exploration of the pathophysiological mechanisms underlying cardiovascular changes in high-altitude environments and provide a theoretical basis for standardized disease diagnosis and treatment.

Intestinal Behçet's disease: A review of clinical diagnosis and treatment

Behçet's disease(BD)is a chronic inflammatory disorder prone to frequent re-currences,with a high predilection for intestinal involvement.However,the ef-ficacy and long-term effects of surgical treatment for intestinal BD are unknown.In the current issue of World J Gastrointest Surg,Park et al conducted a retrospec-tive analysis of 31 patients with intestinal BD who received surgical treatment.They found that elevated C-reactive protein levels and emergency surgery were poor prognostic factors for postoperative recurrence,emphasizing the adverse impact of severe inflammation on the prognosis of patients with intestinal BD.This work has clinical significance for evaluating the postoperative condition of intestinal BD.The editorial attempts to summarize the clinical diagnosis and treatment of intestinal BD,focusing on the impact of adverse factors on surgical outcomes.We hope this review will facilitate more precise postoperative management of patients with intestinal BD by clinicians.

Research Progress in Traditional Chinese Medicine Treatment of Knee Osteoarthritis

Knee osteoarthritis(KOA)is a degenerative disease characterized by pathological changes in the cartilage and subchondral bone of the knee joint.Initially,knee joint pain is the main symptom,and in the later stages,deformities and mobility disorders may occur.Modern medicine lacks effective treatment methods for early and mid stage KOA,and has drawbacks such as significant side effects and high costs.A large number of stud‐ies have confirmed that traditional Chinese medicine has unique advantages in treating KOA,and has obvious advantages such as small trauma,low cost,and definite therapeu‐tic effect,which are gradually being accepted by a large number of KOA patients.The commonly used methods for preventing and treating KOA with traditional Chinese medicine in clinical practice include:oral administration of traditional Chinese medi‐cine,external application of traditional Chinese medicine,fumigation,acupuncture therapy,massage therapy for regulating tendons,and targeted penetration therapy of tra‐ditional Chinese medicine.According to relevant literature,traditional Chinese medicine can significantly alleviate knee joint symptoms and improve knee joint function in patients with knee osteoarthritis,which is of great significance for the prevention and treatment of knee osteoarthritis.This article provides a review of the research progress in the prevention and treatment of KOA using traditional Chinese medicine in recent years.

Effect of Yupingfeng granules on HA and Foxp3^+ Treg expression in patients with nasopharyngeal carcinoma

Objective: To investigate the effect of Yupingfeng on hyaluronic acid(HA) and Foxp3+ Treg in patients with nasopharyngeal carcinoma. Methods: A total of 58 cases of nasopharyngeal carcinoma were divided into two groups, 30 cases in the treatment group, 28 cases in the control group. Patients in two groups were treated with synchronous radiotherapy and chemotherapy treatment, the treatment group was treated with the Yupingfeng granules through oral administration, 10 g/time, tid for 2 courses. The serum Foxp3+ Treg markers of each group were detected by flow cytometry assay before treatment and after treatment, and the level of HA in serum was detected by radio immunoassay. Results: After radiotherapy and chemotherapy, the contents of Foxp3+ Treg and HA were significantly decreased in two groups(P<0.05), and the decrease of treatment group was more significantly(P<0.01). Correlation analysis showed positive correlation between Foxp3+ Treg and HA(P<0.05). After treatment, the incidence of side effects in two groups was significantly decreased. And there was significant difference between two groups(P<0.05). Conclusions: Combined chemotherapy and radiotherapy with Yupingfeng treatment can decrease the levles of Foxp3+ Treg and HA in nasopharyngeal carcinoma patients. Yupingfeng can also effectively reduce the side effect due to radiation and chemotherapy.

Optimizing Designed Variable Speed Control Moment Gyroscopes with Variable Skew Angle

Large torque can be output by the single gimbal control momentum gyroscope (SGCMG) based on the principle of the gyroscopic precession. However, the singularity is a major obstacle to successfully implement the task of the attitude control. The singularity can be avoided by the additional variable flywheel speed of variable speed control moment gyroscopes (VSCMG). Unfortunately, some kind of singularity cannot be effectively avoided. Consequently, the output toque can be only supported by the reaction torque of the flywheel when the singularity is encountered, and the consume power that is determined by the flywheel speed and reaction torque can be greatly increased when the flywheel spin rate over one thousand revolutions per minute. In this paper, the pyramid configuration with variable skew angle of the VSCMG is considered. A new steering law for the VSCMG with variable skew angle is proposed. The singularity that cannot be avoided by the varying flywheel speed can be effectively avoided with assisting of varying the skew angle. Consequently, the requirement of flywheel torque can be reduced. At last, the optimizing VSCMG with variable skew angle can be cast as a multi-objective function with multi-constraints. The particle swarm optimization method is used to solve the optimizing problem. In summary, the VSCMG with variable skew angle can be redesigned with considering of the singularity avoidance and minimizing system power.

Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.

Experimental investigations on effects of gas pressure on mechanical behaviors and failure characteristic of coals

The mechanical behavior of coal is the key factor affecting underground coal mining and coalbed methane extraction.In this study,triaxial compression and seepage tests were carried out on coal at different gas pressures.The mechanical properties and failure process of coal were studied,as well as the acoustic emission(AE)and strain energy.The influence of gas pressure on the mechanical parameters of this coal was analyzed.Based on the conventional energy calculation formula,the pore pressure was introduced through the effective stress formula,and each energy component of coal containing gas was refined innovatively.The contribution of gas pressure to the total energy input and dissipation during loading was quantitatively described.Finally,the influence of gas pressure on coal strength was theo-retically analyzed from the perspectives of MohreCoulomb criterion and fracture mechanics.The results show that the total absorbed energy comprises the absorbed energy in the axial pressure direction(positive)and in the confining pressure direction(negative),as well as that induced by the pore pressure(initially negative and then positive).The absorbed energy in the axial pressure direction accounts for the main proportion of the total energy absorbed by coal.The quiet period of AE in the initial stage shortens,and AE activity increases during the pre-peak stage under high gas pressure.The fractal characteristics of AE in three stages are studied using the correlation dimension.The AE process has different forms of self-similarity in various deformation stages.

Dynamic behaviors of water-saturated and frozen sandstone subjected to freeze-thaw cycles

In high-altitude cold areas,freeze-thaw(F-T)cycles induced by day-night and seasonal temperature changes cause numerous rock mass slope engineering disasters.To investigate the dynamic properties of rock in the natural environment of a high-altitude cold area,standard specimens were drilled from the slope of the Jiama copper mine in Tibet,and dynamic compression tests were performed on watersaturated and frozen sandstone with different numbers of F-T cycles(0,10,20,30,and 40)by the split Hopkinson pressure bar(SHPB)system with a cryogenic control system.The influence of water-saturated and frozen conditions on the dynamic performance of sandstone was investigated.The following conclusions are drawn:(1)With increasing strain rate,the attenuation factor(la)of water-saturated sandstone and the intensifying factor(li)of frozen sandstone linearly increase.As the number of F-T cycles increases,the dependence factor(ld)of water-saturated sandstone linearly decreases,whereas the ld of frozen sandstone linearly increases.(2)The prediction equation of the dynamic compressive strength of water-saturated and frozen sandstone is obtained,which can be used to predict the dynamic compressive strength of sandstone after various F-T cycles based on the strain rate.(3)The mesoscopic mechanism of water-saturated and frozen sandstone’s dynamic compressive strength evolution is investigated.The water softening effect causes the dynamic compressive strength of water-saturated sandstone to decrease,whereas the strengthening effect of pore ice causes it to increase.(4)The decrease in the relative dynamic compressive strength of water-saturated sandstone and the increase in the relative dynamic compressive strength of frozen sandstone can be attributed to the increased porosity.

In vivo astrocyte-to-neuron reprogramming for central nervous system regeneration:a narrative review

The inability of damaged neurons to regenerate within the mature central nervous system(CNS)is a significant neuroscientific challenge.Astrocytes are an essential component of the CNS and participate in many physiological processes including blood-brain barrier formation,axon growth regulation,neuronal support,and higher cognitive functions such as memory.Recent reprogramming studies have confirmed that astrocytes in the mature CNS can be transformed into functional neurons.Building on in vitro work,many studies have demonstrated that astrocytes can be transformed into neurons in different disease models to replace damaged or lost cells.However,many findings in this field are controversial,as the source of new neurons has been questioned.This review summarizes progress in reprogramming astrocytes into neurons in vivo in animal models of spinal cord injury,brain injury,Huntington’s disease,Parkinson’s disease,Alzheimer’s disease,and other neurodegenerative conditions.