Transcriptome Landscape of Human Folliculogenesis Reveals Oocyte and Granulosa Cell Interactions.

The dynamic transcriptional regulation and interactions of human germlines and surrounding somatic cells during folliculogenesis remain unknown. Using RNA sequencing (RNA-seq) analysis of human oocytes and corresponding granulosa cells (GCs) spanning five follicular stages, we revealed unique features in transcriptional machinery, transcription factor networks, and reciprocal interactions in human oocytes and GCs that displayed developmental-stage-specific expression patterns. Notably, we identified specific gene signatures of two cell types in particular developmental stage that may reflect developmental competency and ovarian reserve. Additionally, we uncovered key pathways that may concert germline-somatic interactions and drive the transition of primordial-to-primary follicle, which represents follicle activation. Thus, our work provides key insights into the crucial features of the transcriptional regulation in the stepwise folliculogenesis and offers important clues for improving follicle recruitment in vivo and restoring fully competent oocytes in vitro.

Multilocus Distance-Regulated Sensor Array for Recognition of Polyphenols via Machine Learning and Indicator Displacement Assay.

Developing new strategies to construct sensor arrays that can effectively distinguish multiple natural components with similar structures in mixtures is an exceptionally challenging task. Here, we propose a new multilocus distance-modulated indicator displacement assay (IDA) strategy for constructing a sensor array, incorporating machine learning optimization to identify polyphenols. An 8-element array, comprising two fluorophores and their six dynamic covalent complexes (C1-C6) formed by pairing two fluorophores with three distinct distance-regulated quenchers, has been constructed. Polyphenols with diverse spatial arrangements and combinatorial forms compete with the fluorophores by forming pseudocycles with quenchers within the complexes, leading to varying degrees of fluorescence recovery. The array accurately and effectively distinguished four tea polyphenols and 16 tea varieties, thereby demonstrating the broad applicability of the multilocus distance-modulated IDA array in detecting polyhydroxy foods and natural medicines.

A Supramolecular Fluorescent Sensor Array Composed of Conjugated Fluorophores and Cucurbit[7]uril for Bacterial Recognition.

Bacterial infections have emerged as a significant contributor to global mortality and morbidity rates. Herein, we introduce a dual fluorescence "turn-on" supramolecular sensor array composed of three assembled complexes (C1-C3), formed from three positively charged fluorophores (A1-A3) and one cucurbit[7]uril (CB[7]). The ability of this three-element array to simultaneously recognize 10 bacterial species within just 30 s was remarkable, boasting an impressive 100% accuracy. Additionally, the array excelled at distinguishing among various bacterial mixtures and enabled the quantitative detection of common bacterial strains. Notably, it has been skillfully applied to differentiate 10 bacterial samples in urine, achieving excellent differentiation and showcasing promising potential for medical diagnostic applications.

Stacking Transformation-Triggered Circularly Polarized Luminescence Reversion in γ-Cyclodextrins-Pyrene Co-assembly.

​Considerable attention has been directed towards cyclodextrins (CDs) in the creation of co-assembled CPL-active materials, owing to their intrinsic chiral host cavities and synergistic host-guest interactions. However, achieving reversed CPL emission regulation with single-handedness CDs moiety poses a significant challenge. In this study, we have devised a series of γ-CD-based host-guest complexes comprising dual pyrene imidazolium derivatives with multiple linkers, which exhibit reversed circularly polarized emission. We have uncovered that the transformation of excimer stacking within γ-CD/pyrene complexes contributes to the inverted CPL emissions originating from a single-handed chiral host. This research elucidates the phenomenom of (+)- and (-)-circularly polarized excimer emission (CPEE) within γ-CD, arising from right- and left-handed stacking conformations, respectively.

Risk factors associated with self-rated health among elderly females with different visual abilities in Chinese urban areas: a population-based study.

OBJECTIVE: Self-rated health (SRH) has been documented as an important predictor of quality of life among the elderly and its risk factors are vision-specific among elderly males. The aim of this study was to clarify vision-specific risk factors to SRH among elderly females without dementia in Chinese urban areas. METHODS: From March to November 2012, 2147 elderly women in Liaoning Province of China were selected using a stratified sampling method. After cognitive screening, 1956 participants without dementia were finally enrolled. A questionnaire including SRH, visual ability and factors including demographic characteristics, physical conditions, lifestyle factors, social psychological status and social activities were analyzed. Multivariate logistic regression was used to clarify the association of SRH with risk factors, while stepwise multivariate logistic regression was used to examine the vision-specific associations with SRH. RESULTS: The mean age was 73.6 ± 5.82 (mean ± SD). The percentages of good SRH in good and impaired visual ability groups were 36.2% and 24.4%, respectively. Most characteristics between elderly females with different visual abilities were significantly different. Visual ability had interactions with physical conditions, lifestyle factors and social activities to affect SRH. Among elderly females with good visual ability, depressive symptoms, rather than chronic disease had the strongest association with good SRH followed by marital status, regular diet, going out alone to distant places, taking a walk, smoking and alcohol consumption. In the impaired visual ability group, going out alone to distant places had the strongest association with good SRH followed by chronic disease, filial piety, taking a walk, participating in entertainment, ethnicity, quality of sleep, worrying about falling and alcohol consumption. CONCLUSIONS: Good SRH status was at a low level especially among elderly females with impaired visual ability and the risk factors differed between elderly females with different visual abilities. Social psychological status was crucial for SRH among elderly females with good visual ability whereas physical conditions were prominent for impaired visual ability group.

Quality-of-life improvements in patients after various surgical treatments for pelvic organ prolapse.

OBJECTIVE: To compare the improvements in quality of life of patients with pelvic organ prolapse (POP) treated using various surgical methods. MATERIALS AND METHODS: The PUBMED, MEDLINE and Cochrane Library online databases were searched using the keywords "pelvic organ prolapse", "surgery", "PFDI-20" and "PFIQ-7" for articles published from January 2010 to December 2022 that included quality-of-life scores before and after surgery. RESULTS: Forty-nine articles were include. The mean postoperative PFDI-20 and PFIQ-7 scores decreased by 67.50% and 76.98%, respectively, compared with those before surgery. In 76.9% of patients, this change did not decrease with increased postoperative time. The improvement rate in PFDI-20 scores after colpocleisis did not differ statistically from that after sacrocolpopexy and was significantly higher than that after other procedures. The improvement rate in PFIQ-7 scores after colpocleisis did not statistically differ from that after high uterosacral ligament suspension and was significantly higher than that after other procedures. The improvement rate in PFDI-20 scores after transvaginal mesh-based repair (TVM) did not significantly differ from that after sacrospinous ligament fixation and was significantly lower than that after other procedures except traditional vaginal wall repair. The improvement rate in PFIQ-7 scores after TVM did not significantly differ from that after new procedures and was significantly lower than that after other procedures. CONCLUSIONS: Surgical treatment can significantly improve the quality of life of patients with POP. Colpocleisis may offer more advantages than those of other surgical procedures, and improvement was lower after TVM than after other procedures.

A Dual Fluorescence Turn-On Sensor Array Formed by Poly(para-aryleneethynylene) and Aggregation-Induced Emission Fluorophores for Sensitive Multiplexed Bacterial Recognition.

Bacterial infections have emerged as the leading causes of mortality and morbidity worldwide. Herein, we developed a dual-channel fluorescence "turn-on" sensor array, comprising six electrostatic complexes formed from one negatively charged poly(para-aryleneethynylene) (PPE) and six positively charged aggregation-induced emission (AIE) fluorophores. The 6-element array enabled the simultaneous identification of 20 bacteria (OD600=0.005) within 30s (99.0 % accuracy), demonstrating significant advantages over the array constituted by the 7 separate elements that constitute the complexes. Meanwhile, the array realized different mixing ratios and quantitative detection of prevalent bacteria associated with urinary tract infection (UTI). It also excelled in distinguishing six simulated bacteria samples in artificial urine. Remarkably, the limit of detection for E. coli and E. faecalis was notably low, at 0.000295 and 0.000329 (OD600), respectively. Finally, optimized by diverse machine learning algorithms, the designed array achieved 96.7 % accuracy in differentiating UTI clinical samples from healthy individuals using a random forest model, demonstrating the great potential for medical diagnostic applications.

Machine Learning-Assisted Nanoenzyme/Bioenzyme Dual-Coupled Array for Rapid Detection of Amyloids.

Array-based sensing methods offer significant advantages in the simultaneous detection of multiple amyloid biomarkers and thus have great potential for diagnosing early-stage Alzheimer's disease. Yet, detecting low concentrations of amyloids remains exceptionally challenging. Here, we have developed a fluorescent sensor array based on the dual coupling of a nanoenzyme (AuNPs) and bioenzyme (horseradish peroxidase) to detect amyloids. Various ss-DNAs were bound to the nanoenzyme for regulating enzymatic activity and recognizing amyloids. A simplified sensor array was generated from a screening model via machine learning algorithms and achieved signal amplification through a two-step enzymatic reaction. As a result, our sensing system could discriminate the aggregation species and aggregation kinetics at 200 nM with 100% accuracy. Moreover, AD model mice and healthy mice were distinguished with 100% accuracy through the sensor array, providing a powerful sensing platform for diagnosing AD.

Comparison of the anterior pelvis and levator ani muscle on MRI in women with and without anterior pelvic organ prolapse.

INTRODUCTION AND HYPOTHESIS: The objective was to compare the differences in pelvic and levator ani muscle diameters in women with and without anterior pelvic organ prolapse. METHODS: Three groups were included, including 50 nulliparous women (nulliparous group), 50 women with stage III-IV anterior vaginal prolapse (prolapse group), and 50 women of the same age as the prolapse group but without prolapse (nonprolapse control group). The ischial interspinous diameter (ISD), anterior pelvic area (APA), levator defect score (LDS), levator ani hiatus width (LH-W), H-line, M-line, levator ani plate length, levator ani plate angle, and cervix length (CL) were measured. RESULTS: There were no significant differences in ISD (10.6±0.8 vs 10.6±0.9 cm), LH-W (3.0±0.4 vs 3.3±0.4 cm), or CL (2.9±0.6 vs 3.0±0.5 cm) between the nulliparous group and the nonprolapse control group (p>0.05). However, there were significant differences between them and the prolapsed group (11.2±0.6 cm, 3.6±0.4 cm, 4.2±1.5 cm; p<0.05). There were no significant differences in LDS (0.70±0.61 vs 0.70±0.65) or APA (58.4±8.4 vs 60.1±7.4 cm2) between the nonprolapse control group and the prolapse group (p>0.05), but they were significantly different from those of the nulliparous group (0.08±0.34, 55.1±6.0 cm2) (p<0.05). The area under the receiver-operating characteristic curve for the ISD of nonprolapse control and prolapse groups was 0.713, and the cutoff value was 10.95 cm. CONCLUSIONS: The levator ani hiatus width and cervix length were larger in patients with anterior vaginal prolapse than in those without prolapse. An ischial ISD greater than 10.95 cm was associated with prolapse.

Midterm comparison of laparoscopic high uterosacral ligament suspension and sacrocolpopexy in the treatment of moderate to severe apical prolapse.

INTRODUCTION AND HYPOTHESIS: The objective was to retrospectively analyze the midterm efficacy of laparoscopic high uterosacral ligament suspension (HUS) and sacrocolpopexy (SC) in the treatment of moderate to severe apical prolapse. METHODS: Patients who underwent laparoscopic HUS and SC in our center from 2013 to 2019 with follow-ups were included, consisting of laparoscopic HUS (group A, n=72) or SC (mesh added, group B, n=54). The general data of patients, pelvic organ prolapse quantitative examination (POP-Q) score, Pelvic Floor Distress Inventory short form 20 score (PFDI-20) before and after operation, perioperative conditions, Patient Global Impression of Improvement (PGI-I), and postoperative complications were collected for statistical analysis and comparison between groups. RESULTS: There was no statistical difference in preoperative data between groups. The median follow-up time was 48 months. The objective recurrence rate of group A was higher than that of group B, without statistical significance. One patient in group B had a second operation owing to recurrence. The exposure rate of mesh in group B was 3.70%. There was no significant difference in deviation of POP-Q and PFDI-20 pre- and post-operation. The proportion of new defecation abnormalities in group A was lower. The total hospitalization expenses and surgical consumables in group B were significantly higher than those in group A. CONCLUSIONS: The midterm curative effect of laparoscopic HUS is similar to that of SC in the treatment of moderate to severe apical prolapse. The former has the advantages of less intraoperative blood loss, shorter postoperative hospital stay, lower cost, fewer new defecation abnormalities, and there were no complications related to mesh.

Outcome of a novel porcine-derived UBM/SIS composite biological mesh in a rabbit vaginal defect model.

INTRODUCTION AND HYPOTHESIS: To investigate the tissue reactions of a novel porcine-derived urinary bladder matrix/small intestinal submucosa (UBM/SIS) biological mesh and SIS mesh implanted in a rabbit vaginal defect model. METHODS: Thirty-two rabbits were implanted with UBM/SIS mesh (Group A) and SIS mesh (Group B), respectively. Rabbits were sacrificed at 7, 14, 60, and 180 days after implantation. The tensile strength, elongation at break, and elastic modulus of the tissue were measured using biomechanical methods. The inflammatory response, cell infiltration, vascularization, and collagen fibers were observed. RESULTS: Compared with Group B, the tensile strength and elongation at break of group A was higher at 14, 60, and 180 days. The elastic modulus of group A was lower at 180 days. Inflammatory response of group A was milder at 14, 60, and 180 days. There was more cell infiltration in group A at 7 and 14 days. Vascularization was higher in group A at 7 days and 14 days. The order of collagen in group A was better at 14, 60, and 180 days. The proportion of thick red fibers in both groups showed an increasing trend. At 14 days, group A had more thick red fibers. CONCLUSIONS: The novel UBM/SIS composite mesh had a milder inflammatory response; earlier induction of cell infiltration, angiogenesis, and collagen regeneration. Collagen fibers had a better order. It has a higher tensile strength and greater elongation at break, and can be used as a potential material for the treatment of pelvic organ prolapse.

Machine Learning-Assisted Pattern Recognition of Amyloid Beta Aggregates with Fluorescent Conjugated Polymers and Graphite Oxide Electrostatic Complexes.

Five fluorescent positively charged poly(para-aryleneethynylene) (P1-P5) were designed to construct electrostatic complexes C1-C5 with negatively charged graphene oxide (GO). The fluorescence of conjugated polymers was quenched by the quencher GO. Three electrostatic complexes were enough to distinguish between 12 proteins with 100% accuracy. Furthermore, using these sensor arrays, we could identify the levels of Aß40 and Aß42 aggregates (monomers, oligomers, and fibrils) via employing machine learning algorithms, making it an attractive strategy for early diagnosis of Alzheimer's disease.

One-Component Multichannel Sensor Array for Rapid Identification of Bacteria.

Bacterial infections routinely cause serious problems to public health. To mitigate the impact of bacterial infections, sensing systems are urgently required for the detection and subsequent epidemiological control of pathogenic organisms. Most conventional approaches are time-consuming and highly instrument- and professional operator-dependent. Here, we developed a novel one-component multichannel array constructed with complex systems made from three modified polyethyleneimine as well as negatively charged graphene oxide, which provided an information-rich multimode response to successfully identify 10 bacteria within minutes via electrostatic interactions and hydrophobic interactions. Furthermore, the concentration of bacteria (from OD600 = 0.025 to 1) and the ratio of mixed bacteria were successfully achieved with our smart sensing system. Our designed sensor array also exhibited huge potential in biological samples, such as in urine (OD600 = 0.125, 94% accuracy). The way to construct a sensor array with minimal sensor element with abundant signal outputs tremendously saves cost and time, providing a powerful tool for the diagnosis and assessment of bacterial infections in the clinic.

The systemic-immune-inflammation index predicts the recurrence of atrial fibrillation after cryomaze concomitant with mitral valve surgery.

BACKGROUND AND AIMS: Inflammation plays a key role in the initiation and progression of atrial fibrillation (AF). The systemic inflammation indexes are easily evaluated and predict AF development. However, it's role in prediction of recurrence of AF is unknown. We aim to explore the association between the systemic inflammation indexes and recurrence of AF in patients underwent cryoablation (CryoMaze) concomitant with mitral valve surgery. METHODS: We examined systemic inflammation indexes during perioperative period in 122 patients between 2015 and 2018. Systemic inflammation indexes were developed by systemic immune-inflammation index (SII), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and lymphocytes to monocytes ratio. Univariate and multivariate analyses were performed to examine the association of each markers with recurrence of AF. RESULTS: Of the 122 patients included in this study, 22 patients (18%) experienced AF recurrence after CryoMaze concomitant with mitral valve surgery. There is no significant difference between each systemic inflammation indexes before surgery and recurrence of AF. In univariate analysis, MLR after surgery 3 days, PLR, MPLR, NLR, SII after surgery 7 days were able to predict recurrence of AF. In multivariate analyses, SII ≥ 1696 independently predicted recurrence (OR, 3.719; 95% CI, 1.417-9.760). Interestingly, baseline SII showed no significant in prediction of recurrence. It was sharply elevated after surgery and dropped slowly. In patients of recurrence, SII after 7 days of surgery increased again. CONCLUSIONS: The raised SII again was associated with an increased risk of the postoperative recurrence of AF and independently predicted the late recurrence of AF after CryoMaze concomitant with mitral valve surgery.

Idiopathic retroperitoneal fibrosis with endometrial cancer: a case report and literature review.

BACKGROUND: Retroperitoneal fibrosis is a rare disease characterized by chronic nonspecific inflammation, which leads to clinical compression manifestations of retroperitoneal organs especially ureter. Approximately 70 percent of retroperitoneal fibrosis cases are idiopathic which has no clear etiology. This study reported a rare case of a 48-year-old woman presented with idiopathic retroperitoneal fibrosis and endometrial cancer. CASE PRESENTATION: A 48-year-old woman presented with irregular vaginal bleeding without abdominal pain, bloating or discomfort. The patient was diagnosed iRPF after splenectomy 13 years ago. Then she took prednisone for 2 years and took tamoxifen for about 11 years. She stopped taking the medication from October 2019 to May 2020 and then started taking tamoxifen again until November 2020. Two weeks after she stopped taking tamoxifen, she presented with irregular vaginal bleeding. Gynecological ultrasound revealed a thick endometrium with uneven echo enhancement and blood flow signals. Then diagnostic curettage was performed with pathological examination showed endometroid carcinoma. Later, the patient was admitted to Peking University Third Hospital for surgery. Preoperative imaging examinations, including CT, MRI, and PET/CT, all showed pelvic enlarged lymph nodes and they were highly suspected to have lymph node metastasis. The patient underwent laparoscopic surgical staging and enlarged lymph nodes in the pelvic and aortic regions were removed. Finally, the pathology confirmed that endometrioid adenocarcinoma and fibrosis, but there was no tumor infiltration in these enlarged lymph nodes. The patient is now in good condition. CONCLUSION: This case report stressed the difficulty to distinguish between lymph node metastasis and inflammatory hyperplasia by common imaging methods. Due to increased surgical difficulty among retroperitoneal patients, lymphadenectomy should be carefully evaluated to avoid additional surgical complications and over-treatment.

Design of self-assembly dipeptide hydrogels and machine learning via their chemical features.

Hydrogels that are self-assembled by peptides have attracted great interest for biomedical applications. However, the link between chemical structures of peptides and their corresponding hydrogel properties is still unclear. Here, we showed a combinational approach to generate a structurally diverse hydrogel library with more than 2,000 peptides and evaluated their corresponding properties. We used a quantitative structure-property relationship to calculate their chemical features reflecting the topological and physicochemical properties, and applied machine learning to predict the self-assembly behavior. We observed that the stiffness of hydrogels is correlated with the diameter and cross-linking degree of the nanofiber. Importantly, we demonstrated that the hydrogels support cell proliferation in culture, suggesting the biocompatibility of the hydrogel. The combinatorial hydrogel library and the machine learning approach we developed linked the chemical structures with their self-assembly behavior and can accelerate the design of novel peptide structures for biomedical use.

Long-Term Observation on Postoperative Recurrence and Complications of Transvaginal Mesh Surgery for Pelvic Organ Prolapse.

OBJECTIVE: This study aims to evaluate the risk factors for subjective recurrence and complications of patients who underwent transvaginal synthetic mesh surgery. DESIGN: This retrospective cohort study included patients who received transvaginal mesh (TVM) surgery between January 2005 and June 2019. METHODS: The information of patients was collected, including basic characteristics, subjective recurrence, and mesh-related complications. The clinical characteristics of patients with and without subjective recurrence were compared. The sexual activities of patients before and after the operation were recorded. SPSS 20.0 was used for the statistical analysis. RESULTS: A total of 257 patients were included. Among them, 62 (24.1%) patients were lost to follow-up. The median follow-up time was 80 months (12 months, 170 months). Finally, 195 patients were followed up, 11 (5.6%) patients had a subjective recurrence of pelvic organ prolapse, and 26 (13.3%) patients had mesh-related complications (11 patients with de novo pain and 15 patients with mesh exposure). We found significant differences in age (68.9 ± 5.1 vs. 63.4 ± 5.8 years old), years of postmenopause (17.5 ± 6.3 vs. 13.3 ± 6.9 years), previous hysterectomy (27.3% vs. 6.0%), and concomitant hysterectomy (45.5% vs. 81.0%) between patients with and without subjective recurrence (p < 0.05). The mesh exposure proportion of patients with total vaginal mesh (47.6%) was significantly higher than that with anterior vaginal mesh (2.9%) (p < 0.05). Furthermore, 6.7% of sexually active patients reported de novo dyspareunia. LIMITATION: The investigators could only record the subjective recurrence of patients, and thus there is a lack of objective recurrence data. CONCLUSION: Age, years of postmenopause, and previous hysterectomy are risk factors for subjective recurrence of TVM surgery; however, concomitant hysterectomy is a protective factor. Mesh exposure is the most common complication, especially for total vaginal mesh repair surgery.

Evaluation of pelvic floor muscle function (PFMF) in cervical cancer patients with Querleu-Morrow type C hysterectomy: a multicenter study.

INTRODUCTION: To evaluate the pelvic floor muscle function (PFMF) of cervical cancer patients after type QM-C hysterectomy and to explore the relationship between decreased PFMF and related factors. METHODS: This was a multi-centered retrospective cohort study. 181 cervical cancer patients who underwent type QM-C hysterectomy were enrolled from 9 tertiary hospitals. Strength of PFMF were measured using neuromuscular apparatus (Phenix U8, French). Risk factors contributing to decreased PFMF were analyzed by univariate and multivariate ordinal polytomous logistic regression. RESULTS: Totally 181 patients were investigated in this study. 0-3 level of type I muscle fibre strength (MFSI) was 52.6% (95/181), 0-3 level of type IIA muscle fibre strength (MFSIIA) was 50% (91/181). Subjective stress urinary incontinence was 46% (84/181), urinary retention was 27.3% (50/181), dyschezia was 41.5% (75/181), fecal incontinence was 9% (18/181). ① MFSI: Multivariate ordinal polytomous logistic regression shows that the follow-up time (p < 0.05), chemotherapy and radiotherapy (p = 0.038) are independent risk factors of MFSI's reduction after type QM-C hysterectomy. ② MFSIIA: multivariate ordinal polytomous logistic regression shows that the follow-up time (p < 0.05) are independent risk factors of MFSIIA's reduction after type QM-C hysterectomy. The pelvic floor muscle strength (PFMS) increased after 9 months than in 9 months after operation, which showed that the PFMS could be recovered after operation. CONCLUSIONS: We advocate for more attention and emphasis on the PFMF of Chinese female patients with cervical cancer postoperation. PEKING UNIVERSITY PEOPLE'S HOSPITAL: PFMF after QM-C hysterectomy has not been analyzed by current study. The contribution is that patients with radical hysterectomy should do pelvic floor rehabilitation exercises in 3 months after operation. Clinical Trails NCT number of this study is 02492542.

Axial Stress Measurement of Steel Tubes Using Ultrasonic Guided Waves.

Axially loaded steel tubes are widely used as primary structural members in civil engineering structures. In this paper, a stress measurement method for axially loaded steel tubes is developed based on the linear relationship between the group velocity of guided waves in the steel tube and the stress of the steel tube. The propagation modes of guided waves in a typical steel tube are analyzed using semi-analytical finite element method. A torsional mode T(0,1) is adopted to conduct the measurement. Experiments are carried out to calibrate the linear relationship between the group velocity of guided waves in a steel tube and the stress of the steel tube. The calibrated linear relationship is verified by another round of experiments on the same steel tube specimen. There is an average error of 8.2% between the stresses predicted by the calibrated linear equation and those obtained from strain gauges. Via this study, the guided wave-based stress measurement method has been successfully extended to axially loaded steel tubes.

Crack Detection of Threaded Steel Rods Based on Ultrasonic Guided Waves.

Fatigue cracks are typical damage of threaded steel rods under dynamic loads. This paper presents a study on ultrasonic guided waves-based, fatigue-crack detection of threaded rods. A threaded rod with given sizes is theoretically simplified as a cylindrical rod. The propagation characteristics of ultrasonic guided waves in the cylindrical rod are investigated by semi-analytical finite element method and the longitudinal L(0, 1) modal ultrasonic guided waves in low frequency band is proposed for damage detection of the rod. Numerical simulation on the propagation of the proposed ultrasonic guided waves in the threaded rod without damage shows that the thread causes echoes of the ultrasonic guided waves. A numerical study on the propagation of the proposed ultrasonic guided waves in the threaded rod with a crack on the intersection of the smooth segment and the threaded segment shows that both linear indexes (Rf and ARS) and nonlinear indexes (ßre' and ß') are able to detect the crack. A constant-amplitude tensile fatigue experiment was conducted on a specimen of the threaded rod to generate fatigue cracks in the specimen. After every 20,000 loading cycles, the specimen was tested by the proposed ultrasonic guided waves and evaluated by the linear indexes and nonlinear indexes. Experimental results show that both the linear and nonlinear indexes of the ultrasonic guided waves are able to identify the crack before it enters the rapid growth stage and the nonlinear indexes detect the crack easier than the linear indexes.