Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A.

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15 PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A.

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10 TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60 TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

[5 cases of bradyarrhythmia caused by adonis amurensis poisoning].

Adonis amurensis is a herb with the effect of cardiotonic and diuretic.Overdose can lead to various bradyarrhythmia and gastrointestinal reaction. This article analyzed the treatment process of 5 patients with bradyarrhythmia caused by adonis amurensis to enhance clinical doctors' understanding of the treatment principles for adonis amurensis poisoning.

[Fuzheng Huayu capsules reducing development of hepatocellular carcinoma in cirrhotic patients with chronic hepatitis B based on the ratio of neutrophils/lymphocytes].

Objective: To explore the advantage of Fuzheng Huayu capsule in patients with hepatitis B cirrhosis based on neutrophil/lymphocyte ratio (NLR) risk stratification in reducing the incidence of hepatocellular carcinoma (HCC). Methods: 916 cases diagnosed with hepatitis B cirrhosis and followed up for five years from January 2011 to January 2016 at Beijing Ditan Hospital Affiliated with Capital Medical University were included, and clinical data were collected. Patients were divided into a combination group and an antiviral group according to whether they were treated with anti-fibrosis for≥6 months. The antiviral group was treated with entecavir or tenofovir disoproxil, while the combination group was treated with Fuzheng Huayu capsules based on the antiviral therapy. The incidence of HCC was compared between the two groups of patients within five years. The advantaged groups treated with Fuzheng Huayu capsule were explored based on NLR risk stratification. The independent sample t-test and Mann-Whitney U test were used to compare measurement data between two groups. Categorical variable data were compared using either the χ(2) test or Fisher's exact probability method. The incidence of HCC in the two groups of patients was analyzed through the Kalplan-Merier curve and compared using the log-rank method. Results: There were 299 (32.6%) and 617 (67.4%) cases in the combined group and the antiviral group, respectively. A total of 154 (16.8%) patients developed HCC during the follow-up period. The five-year cumulative incidence of HCC in the combination group was lower than that in the antiviral group (10.7% vs. 19.8%, χ(2) = 11.848, P = 0.000 4). Patients with baseline NLR>3 had an increased risk of HCC. According to NLR risk stratification, there were 191 cases in the low-risk group (NLR<1.4), 462 cases in the medium-risk group (NLR1.4 ~ 3.0), and 263 cases in the high-risk group (NLR>3). Among medium to high-risk patients, the incidence of HCC was significantly reduced in the combination group (11.5% vs. 19.4%, χ(2) = 4.519, P = 0.029; 13.2% vs. 26.2%, χ(2) = 5.258, P = 0.019), while there was no statistically significant difference in the incidence of HCC among the low-risk group (P = 0.38). Conclusion: Compared with antiviral treatment alone, Fuzheng Huayu capsules combined with antiviral treatment can better reduce the five-year HCC incidence rate in patients with hepatitis B cirrhosis. Medium-and high-risk patients with NLR stratification are the most advantageous population to be treated with Fuzheng Huayu capsules.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst.

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory (LHAASO) of the bright GRB 221009A, which serendipitously occurred within the instrument's field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger and then rose to a peak ~10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle of ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

[Characteristics of autonomic neuropathy in patients with vestibular migraine].

Objective: To investigate the characteristics of autonomic neuropathy in patients with vestibular migraine (VM) by sympathetic skin reflex (SSR) and R-R interval variation (RRIV). Methods: Seventy-three patients with interseizure VM and 36 healthy controls in the Department of Neurology affiliated to Shanghai Fourth People's Hospital of Tongji University from November 1, 2019 to December 31, 2021 were prospectively enrolled. SSR and RRIV were performed and relevant parameters were recorded, including SSR latency, SSR amplitude, RRIV during calm breathing (R%), RRIV during deep breathing (D%), RRIV difference between deep breathing and calm breathing (D%-R%), RRIV ratio between deep breathing and calm breathing (D%/R%), and the difference and correlation of various parameters between VM patients and healthy controls were analyzed. Results: Among the 73 patients with VM, there were 12 males and 61 females, and aged (46±13) years. While among 36 healthy controls, there were 6 males and 30 females, and aged (46±7) years. Among the 73 VM patients, abnormal SSR, abnormal RRIV, abnormal SSR and RRIV, and abnormal SSR or RRIV was detected in 38 cases (52%), 17 cases (23%), 11 cases (15%) and 44 cases (60%), respectively. Compared with healthy controls, the lower extremity SSR latency [(1 719±289) ms] in VM patients was longer than that in control group [(1 500±349) ms] (P=0.001), but the upper extremity SSR amplitude [1.6 (0.8, 3.0) mV] was lower than that in control group [2.6 (1.8, 4.2) mV] (P=0.006). SSR amplitude, R% and D% were negatively correlated with age in VM patients (rs=-0.311, P=0.007; rs=-0.237, P=0.043; rs=-0.263, P=0.024, respectively). SSR of lower extremity in VM patients was longer than that of upper extremity [(1 719±289) ms vs (1 244±185) ms, P<0.001], but the amplitude of lower extremity was lower than that of upper extremity [0.8 (0.3, 1.7) mV vs 1.6 (0.8, 3.0) mV, P<0.001]. SSR latency of upper limb was positively correlated with SSR latency of lower limb (r=0.436, P<0.001), the amplitude of upper limb was positively correlated with amplitude of lower limb (rs=0.456, P<0.001), and D% was positively correlated with R% (rs=0.357, P=0.002). Conclusion: The autonomic neuropathy during VM interphase features with imbalance between sympathetic and parasympathetic nervous system, and the sympathetic nerve function is mainly impaired.

[Discussion on the use of occupational contraindication cardiovascular disease in Technical Specifications for Occupational Health Surveillance (GBZ 188-2014)].

Technical Specifications for Occupational Health Surveillance (GBZ 188-2014) has played an important role in screening occupational contraindications and preventing occupational diseases since its implementation. However, during the use of occupational health examination, we found that the use of occupational contraindication on cardiovascular disease was not "homogenized" due to the differences in the understanding of various physical examination institutions. Therefore, this paper mainly discussed the connotation and quantitative standards of organic heart disease, arrhythmia, hypertension in the occupational contraindication cardiovascular disease in the specification for "homogenization".

Effect of avian influenza virus subtype H9N2 on the expression of complement-associated genes in chicken erythrocytes.

1. The H9N2 subtype avian influenza virus can infect both chickens and humans. Previous studies have reported a role for erythrocytes in immunity. However, the role of H9N2 against chicken erythrocytes and the presence of complement-related genes in erythrocytes has not been studied. This research investigated the effect of H9N2 on complement-associated gene expression in chicken erythrocytes.2. The expression of complement-associated genes (C1s, C1q, C2, C3, C3ar1, C4, C4a, C5, C5ar1, C7, CD93 and CFD) was detected by reverse transcription-polymerase chain reaction (RT-PCR). Quantitative Real-Time PCR (qRT-PCR) was used to analyse the differential expression of complement-associated genes in chicken erythrocytes at 0 h, 2 h, 6 h and 10 h after the interaction between H9N2 virus and chicken erythrocytes in vitro and 3, 7 and 14 d after H9N2 virus nasal infection of chicks.3. Expression levels of C1q, C4, C1s, C2, C3, C5, C7 and CD93 were significantly up-regulated at 2 h and significantly down-regulated at 10 h. Gene expression levels of C1q, C3ar1, C4a, CFD and C5ar1 were seen to be different at each time point. The expression levels of C1q, C4, C1s, C2, C3, C5, C7, CFD, C3ar1, C4a and C5ar1 were significantly up-regulated at 7 d and the gene expression of levels of C3, CD93 and C5ar1 were seen to be different at each time point.4. The results confirmed that all the complement-associated genes were expressed in chicken erythrocytes and showed the H9N2 virus interaction with chicken erythrocytes and subsequent regulation of chicken erythrocyte complement-associated genes expression. This study reported, for the first time, the relationship between H9N2 and complement system of chicken erythrocytes, which will provide a foundation for further research into the prevention and control of H9N2 infection.

[Solitary fibrous tumor in choroid: a clinicopathologic analysis of two cases].

Solitary fibrous tumor (SFT) is an uncommon spindle cell tumor that occurs mainly in the pleura, but also in other parts of the body. Intraocular SFT is very rare. This paper reports 2 cases of choroidal SFT which were diagnosed by clinical, imaging, histopathological and immunohistochemical staining. The patient remained asymptomatic with no sign of recurrence and metastasis after operation.

[Association between serum sex hormone-binding globulin and non-alcoholic steatohepatitis].

Objective: To investigate the association between serum sex hormone-binding globulin (SHBG) and non-alcoholic steatohepatitis (NASH). Methods: In this cross-sectional study, a total of 371 middle-aged and young obese patients who were hospitalized and underwent liver puncture in Nanjing Drum Tower Hospital from January 2016 to April 2021 were included. The population was divided into control group (n=43) and non-alcoholic fatty liver disease (NAFLD) group (n=328) based on the non-alcoholic fatty liver disease activity score. Subjects in NAFLD group were further divided into non-alcoholic fatty liver (NAFL) (n=60), uncertain-NASH (n=172), and NASH (n=96). Serum SHBG was tested in patients with NAFLD who were divided into three subgroups according to tertiles. The liver pathological characteristics in different SHBG level subgroups were compared. The risk factors of NASH were analyzed by logistic regression. The prediction model of NASH noninvasive diagnosis was established by forward stepwise regression, and the diagnostic value of non-invasive model for NASH was evaluated by receiver operating characteristic (ROC) curve. Results: The median age in patients were (32±10) years old with a body mass index of (39.16±6.58) kg/m², including 236 females (63.6%). Serum SHBG level [M (Q1, Q3)] in NAFLD group was significantly lower than that in control group [16.90 (11.43, 23.00) vs. (23.45 (15.40, 31.22) mmol/L, P<0.05], and progressively diminished in NAFL, uncertain-NASH and NASH subgroups [(22.24±10.47), (20.57±19.58), (15.80±8.74) mmol; P for trend<0.05]. Compared with the high-leveled SHBG subgroup, the steatosis score (2.09±0.80 vs. 1.51±0.72, P<0.01) and lobular inflammation score (1.10±0.68 vs. 0.85±0.68, P<0.05) were significantly higher in the low-leveled SHBG group. Multivariate logistic regression analysis indicated that lower serum SHBG level was an independent risk factor for NASH (OR=2.527, 95%CI: 1.296 to 4.928, P<0.05). The area under ROC curve of SHBG combined with aspartate aminotransferase in predicting NASH in NAFLD patients was 0.752 (95%CI: 0.696 to 0.809). Conclusion: Low serum SHBG level is associated with NASH.

[Effects of parity on nutrition and health status of Chinese women of childbearing age].

Objective: To analyze effects of parity on women's nutrition and health status. Methods: This study was based on the data bank of "Chinese Nutrition and Health Surveillance of Children and Adolescents Aged 0-17 years old and Lactating Mothers from 2016 to 2017". Using a multi-stage stratified random sampling method, 17 771 women at 0 to 24 months postpartum from 31 provinces in Mainland China were included in this study. Questionnaires were used to collect data on women's general demographic characteristics, parity, mode of delivery, pre-pregnancy weight, pre-delivery weight, diseases before and during pregnancy, postpartum hemorrhage. Current body height, body weight, waist circumference, and blood pressure were measured. Blood hemoglobin, blood glucose and blood lipids were detected. Pre-pregnancy BMI, gestational weight gain, postpartum weight retention, postpartum BMI, the rates of anemia, hypertension, diabetes, and dyslipidemia were calculated. Survey sample weights were calculated according to the sampling design and number of children under 2 years old from the sixth population census data of China. Effects of parity on the observational indicators after adjusting for confounding factors were analyzed by multivariate linear regression and multivariate logistic regression. Results: The age of 17 771 women was (29.5±5.0) years old, 12.2% (2 172) were over 35 but less than 40 years old, and 3.2% (563) were over 40 years old; the women with one parity, two parities, and three parities accounted for 47.3% (8 413), 48.5% (8 620) and 4.2% (738), respectively; urban women accounted for 49.9% (8 875), and rural women accounted for 50.1% (8 896). The results from multivariate linear regression showed that the pre-pregnancy BMI of women with two and three parities was 0.55 kg/m2 and 0.76 kg/m2 higher than women with one parity, respectively; the results of multivariate logistic regression showed that the OR(95%CI) of pre-pregnancy anemia was 1.45(1.04-2.02) for women with three parities compared with women with one parity, and the OR(95%CI) of anemia during pregnancy for women with two parities was 1.20(1.06-1.35) compared with women with one parity. Conclusion: Parity is associated with pre-pregnancy BMI and risk of anemia before and during pregnancy in women of reproductive age.

Antibacterial activity and mechanism of chloroform fraction from aqueous extract of mugwort leaves (Artemisia argyi L.) against Staphylococcus aureus.

In this work, the antibacterial activity and mechanism of chloroform fraction obtained from aqueous extract of mugwort leaves against Staphylococcus aureus were investigated. The extract showed obvious antibacterial activity against S. aureus which the minimum inhibitory concentration and minimum bactericidal concentration were determined to be 3·0 and 6·0 mg ml-1 respectively. The mechanism study suggested that the extract could destroy the integrity of the S. aureus cell walls and increase the permeability of cell membrane in a certain concentration, but it could not kill S. aureus in a short time. Instead, the extract could make bacteria in a state of apoptosis for a long time, interfere with the normal physiological metabolism of bacteria, and eventually make bacteria die, which was confirm by scanning electronic microscope.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO.

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

The extended submuscular fibroadipose tissue (SMFAT) resection and ladder suture technique for patients with a puffy SMFAT upper eyelid.

BACKGROUND: In East Asians, a common method to ameliorate puffy eyelids is to resect the excess orbital fat and the orbicularis. However, in some patients, a satisfactory improvement cannot be achieved because of the thick submuscular fibroadipose tissue (SMFAT) and minimal orbital fat. The SMFAT lies between the orbicularis and the orbital septum and can also be found in the pretarsal area. It is responsible for puffy eyelids and the slackening of the tissue after removal. In this study, we combined an extended SMFAT resection with the ladder suture technique to correct puffy SMFAT eyelids. METHOD: A total of 76 patients with a thick SMFAT and minimal orbital fat were recruited. The thick SMFAT, which included the soft tissue near the artificial fold and the pretarsal area soft tissue, was resected. The ladder suture technique was performed by positioning the stitch 1 mm below the orbicularis margin after a skin flap margin puncture. The esthetic effect was evaluated pre-operatively and at 12 months post-operatively. RESULTS: The pre-operative thickness of the SMFAT and full layers of the eyelid were 0.27 ± 0.03 mm and 2.01 ± 0.11 mm, respectively. One year after surgery, the thickness was 0.08 ± 0.02 mm and 1.68 ± 0.14 mm, respectively (p < 0.05). The post-operative upper eyelash lift-up angle and the eyelash exposure length were significantly increased on both sides compared with the pre-surgery (p < 0.05). No patients experienced complications. CONCLUSION: An extended SMFAT resection combined with the ladder suture technique can effectively correct puffy SMFAT eyelids without complications.

Tau Pathologies Mediate the Associations of Vascular Risk Burden with Cognitive Impairments in Non-demented Elders: The CABLE Study.

BACKGROUND: Studies suggested that vascular dysfunction might increase the risk of developing Alzheimer's disease (AD), but the underlying mechanisms still remain obscure. OBJECTIVE: To evaluate the associations of vascular risk burden with AD core pathologies and investigate the effects of AD core pathologies on relationships between vascular risk burden and cognitive impairments. DESIGN: The Chinese Alzheimer's Biomarker and LifestyLE (CABLE) study was principally focusing on aging, as well as the risk factors and biomarkers of AD initiated in 2017. SETTING: The CABLE study was a large cohort study established in Qingdao, China. PARTICIPANTS: A total of 618 non-demented elders were obtained from CABLE study. MEASUREMENTS: The general vascular risk burden was assessed by the Framingham General Cardiovascular Risk Score (FGCRS). Multivariate linear regression analyses were performed to evaluate the associations of FGCRS with cerebrospinal fluid (CSF) AD biomarkers and cognition. Casual mediation analyses were performed to investigate the mediating effects of AD biomarkers on cognition. RESULTS: Increased FGCRS was related to higher levels of CSF total tau (t-tau, p < 0.001), phosphorylated tau (p-tau, p < 0.001) as well as the ratio of t-tau and amyloid-ß 42 (t-tau/Aß42, p = 0.010), and lower Chinese-Modified Mini-Mental State Examination (CM-MMSE, p = 0.010) score. Stratified analysis indicated that age modified the associations, with FGCRS being significantly associated with tau pathology (p < 0.001 for t-tau and p-tau) in middle-aged group (<65 years old), instead of older group. The influences of FGCRS on cognitive impairments were partially mediated by tau pathologies (a maximum proportion of 20.9%). CONCLUSIONS: Tau pathology might be a pivotal mediator for effects of vascular risk on cognitive decline. Early and comprehensive intervention for vascular risk factors might be a potential approach to delaying or preventing cognitive impairment and AD.

Tumor microenvironment and its clinicopathological and prognostic associations in surgically resected cutaneous angiosarcoma.

PURPOSE: Cutaneous angiosarcoma (CAS) is a rare but typically aggressive malignant vascular neoplasm of the skin. Tumor microenvironment (TME) of CAS and its associations with baseline clinicopathological features and patient outcomes are very important, especially when considering the recent advances in understanding of the tumor biology. METHODS/PATIENTS: We retrospectively reviewed medical records of patients who underwent surgical resection for CAS at a tertiary Hospital. The pretreated specimens were evaluated by immunohistochemistry for programmed cell death protein 1 (PD-1) and its ligand (PD-L1), densities of tumor infiltrative lymphocytes (TILs) (CD3+, CD4+, CD8+, CD45RO+, FoxP3+), as well as c-MYC and Ki-67 expressions. Overall survival (OS) was estimated by Kaplan-Meier method and compared with Log-rank test. RESULTS: A total of 21 CAS patients were identified. Median age was 67 (ranges: 20-81) years, 14 (66.7%) were male, and over 50% had lesions of scalp. Histopathological examination showed a predominantly spindle cell type (57.1%). All patients underwent surgery, 16 (76.2%) were treated further. PD-L1 was positively stained (> 1%) in tumor cells (42.9%) and TILs (23.8%). PD-1 expression (> 1%) was identified in TILs of 11 (52.4%) cases. PD-1/PD-L1 expressions were significantly associated with the higher densities of CD3+, CD4+, CD8+, CD45RO+, and Foxp3+ TILs, but not with patient characteristics or c-MYC or Ki-67 expression. Median OS was 18.5 months (95% CI 6.0-35.9), although no prognostic significance was observed with respect to any clinicopathological features. CONCLUSION: We characterized TME and its clinical and prognostic association in CAS. PD-1/PD-L1 expressions were significantly associated with TILs subtypes but not with OS.

Longitudinal investigations of anatomical and morphological development of the gastrointestinal tract in goats from colostrum to postweaning.

The digestive tract development in goat kids around weaning is vital to the establishment of digestion and absorption function, growth, and health of adults. The objective was to explore the effects of age and solid feed on the anatomical and morphological development of the gastrointestinal tract of Laiwu Black goat kids. Forty-eight female Laiwu Black goats at 8 ages (1, 7, 14, 28, 42, 56, 70, and 84 d; 6 goats per group) were selected and killed for anatomical and morphological analysis. The goats experienced the following 4 diet phases: maternal colostrum (MC; d 1, d 7), maternal milk (MM; d 14, d 28), maternal milk plus solid diet (MMSD; d 42, d 56) and only solid diet (OSD; d 70, d 84). The body and carcass weights were not significantly changed during MC and MM phases but changed during the MMSD phase. The absolute growth of body and carcass weights were higher in the MMSD phase than in MM phase. In addition, the dressing percentage was the highest in the MMSD phase. The body size indices evolved progressively and increased over time. The percentage of internal and external organs to body weight decreased over time, whereas the percentage to complex stomach percentage increased. The rumen and omasum weight experienced synchronous absolute growth over time, especially in the OSD phase. In contrast, the absolute growth of the reticulum and abomasum was the highest in MMSD and MC phases, respectively. After weaning, the goats showed the highest papillae height, lamina propria, muscle layer thickness, and epithelial thickness. The OSD phase showed the highest colonic mucosa thickness, ileal villus height, and ileal muscle layer thickness. The crypt depth was higher in the MMSD phase than in the MM phase. Moreover, the crypt depth and muscle layer thickness of jejunum increased over time. Furthermore, duodenal crypt depth, muscle layer thickness, and epithelial thickness increased in the OSD phase compared with other stages. In conclusion, the histological investigation supports the improvement of the morphological development of the digestive tract and the growth performance in the solid feed phase. It is recommended to add solid food as early as 4 wk old.

Low dietary phosphorus impairs keel bone health and quality in laying hens.

1. Phosphorus (P) is a necessary nutrient for egg production and bone quality in poultry diets. To investigate the effects of low dietary available P (avP) on keel bone, 180 laying hens were fed either a control (C, 0.3% avP) or low phosphorus (LP, 0.15% avP) diet from 20-36 weeks of age (WOA). Each diet was replicated in six cages with 15 birds per cage. Keel samples were collected at 24, 28, 32, and 36 WOA to measure indicators.2. The incidence of keel bone damage in the LP group was higher than C group and increased with age throughout the experiment period. Keel bone length from laying hens in the LP group was shorter than C group (P < 0.05) at 32 and 36 WOA.3. The mRNA expression of receptor activator of nuclear factor kappa-B ligand (RANKL) and ratio of RANKL to osteoprotegerin (OPG) were upregulated (P < 0.05), and that of sclerostin and OPG was downregulated (P < 0.05) in the LP group in comparison to hens in the C group. Meanwhile, mRNA expression of the integrin-binding sialoprotein was increased at 24 and 28 WOA (P < 0.05), and decreased at 32 and 38 WOA (P < 0.05) in the LP group.4. Laying hens in LP group had increased trabecular separation and bone surface fraction (P < 0.05), decreased bone volume, bone volume fraction, trabecular number and thickness, and bone mineral density (P < 0.05) at 32 WOA. The LP-fed hens had increased K, Ti, Mn, Fe, Zn, Se, Sr and Pb bone concentrations (P < 0.05), and decreased P and TI bone concentrations (P < 0.05) at 36 WOA.5. Feeding hens a P-deficient diet with 0.15% avP and 3.37% Ca during the laying period impaired keel bone quality, which could be related to the osteoporosis.