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Abstract Background Tricuspid regurgitation (TR) is common in patients evaluated by echocardiography. However, the prevalence and contributing factors of the disease remain limited. This hospital-based study was designed to analyze adult patients first diagnosed with tricuspid regurgitation by Doppler echocardiography to determine the prevalence and characteristics of clinically meaningful TR. Methods A total of 22,317 patients over the age of 18 who underwent echocardiography at the Cardiac Ultrasound Center of the First Affiliated Hospital of Guangdong Pharmaceutical University from July 1, 2015 to December 31, 2019 were collected. We collected basic information about the patients, including age, gender, history of heart disease, etc. Patients with valvular heart disease were assessed by transthoracic echocardiography. According to the degree of regurgitation and regurgitation, TR was divided into 6 grades (0–5). Pericardial effusion was recorded and bilateral atrial and ventricular diameters were measured. Logistic regression analysis was used to assess risk factors for significant TR (≥ grade 2 reflux). Results A total of 2299 significant TR cases were found in people over 18 years old, accounting for 10.3% of the total population. The occurrence of TR was found to be closely related to age. The prevalence rates of significant TR in different groups were: 3.3% in the younger than 45-year-old group, 4.1% in the 46-55-year-old group, 5.8% in the 56-65-year-old group, 10.1% in the 66-75-year-old group, and the prevalence of significant TR rose directly to 22.3% in patients over 75-year-old group. Further logistic regression analysis showed that male, age, pacemaker, congenital heart disease, pericardial effusion, pulmonary hypertension, mitral regurgitation, left ventricular diastolic dysfunction and aortic regurgitation were associated with the occurrence of significant TR. Both RVD and RA-1 were effective predictors of significant TR, with RVD ≥ 33.5 mm having a sensitivity of 0.638, specificity of 0.675, and ROC curve area of 0.722. The sensitivity of RA1 ≥ 45.5 mm was 0.652, the specificity was 0.699, and the area under the ROC curve was 0.736. Conclusions TR is common in people undergoing echocardiography. Gender, age, pacemaker implantation, congenital heart disease, pericardial effusion, pulmonary hypertension, mitral insufficiency, and aortic insufficiency are the influencing factors of TR.

This work investigates the nonlinear response of a conical premixed flame to dual-frequency excitation through experiments and G-equation analysis. In addition to the responses at excitation frequencies, f1 and f2, a notable flame response can also be identified at the difference frequency, fd. The fd response is particularly significant in the high-frequency regime, characterized by multiple wavelengths of both f1 and f2 on the flame front. This distinct behavior of difference-frequency response can be attributed to the spatial superposition of the intensified flame fluctuation waves at the two forcing frequencies. As the excitation enhances at either f1 or f2, the nonlinear effect suppresses the responses of the upper-part flame at both f1 and f2 while promoting the bulk flame response at fd. Based on a third-order expansion of the G-equation, it is shown that the nonlinear flame dynamics necessarily generate the observed interaction component when the flame is perturbed by dual-frequency excitations. The present results emphasize the importance of nonlinear flame dynamics in inducing flame responses at interaction frequencies, offering insights into thermoacoustic oscillations of multiple frequencies.

In the 16^th^ and 17^th^ centuries, under the influence of the Portuguese Empire's overseas expansion and cultural integration, the island city of Macau became an important international trading port in the Eastern Sea, with close ties to the Asian port cities governed by Portugal. This study introduces a new method for comparing urban morphological layouts using machine learning and investigates the potential benefits of combining urban morphological analysis with machine learning techniques. In addition, a combination of urban morphology theory and machine learning is used to excise samples of urban morphology from Portuguese urban geographical information maps. The morphological characteristics of port city areas are further extracted, and training labels for typical Portuguese urban textures are established. Using the YOLOv4 object detection algorithm, the results are compared with the urban textures of typical island and port cities of the Asian Silk Road---Goa in India, Malacca in Malaysia, Macau in China, and Dili in Timor-Leste---revealing the similarities and differences among the port cities in Asia influenced by traditional Portuguese urban practices. The results reveal the relationship between maritime trade and urban form.

Abstract Numerous novel and effective therapeutic agents and clinical trials addressing castration-resistant prostate cancer (CRPC) were reported during the 2023 American Society of Clinical Oncology-Genitourinary (ASCO-GU) Cancers Symposium. Notably, radionuclide drug conjugates (RDC), specifically 177Lu/111In-J591 and 225Ac-J591, exhibited enhanced therapeutic efficacy in treating patients with CRPC. Furthermore, promising treatment approaches for CRPC included dual anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and anti-programmed death-1 (PD-1) blockade in rare tumors (DART)-Lorigerlimab, prostate stem cell antigen (PSCA)-directed chimeric antigen receptor (CAR)-T cell immunotherapy-BPX-601, and protein kinase inhibitor (AKTi)-CAPltello-280. We have summarized the latest CRPC treatment strategies presented at the 2023 ASCO-GU Cancers Symposium, along with recent advances in CRPC clinical trials.

Abstract Antibody–drug conjugates (ADCs) combine the cytotoxicity of small-molecule drugs with antibody targeting. Due to their precise and powerful effect, they have become a new hotspot and an important trend in the research and development of anti-tumor antibody drugs. Every year, exciting new developments and innovations in the treatment of urological tumors are introduced at the American Society of Clinical Oncology-Genitourinary (ASCO-GU) Cancers Symposium. In this article, we summarize some of the most impressive advances in new clinical trials and clinical data on ADCs in the 2023 ASCO-GU Cancers Symposium for the treatment of urothelial carcinoma.

Abstract Bladder cancer (BC) is a clinical challenge worldwide with late clinical presentation, poor prognosis, and low survival rates. Traditional cystoscopy and tissue biopsy are routine methods for the diagnosis, prognosis, and monitoring of BC. However, due to the heterogeneity and limitations of tumors, such as aggressiveness, high cost, and limited applicability of longitudinal surveillance, the identification of tumor markers has attracted significant attention in BC. Over the past decade, liquid biopsies (e.g., blood) have proven to be highly efficient methods for the discovery of BC biomarkers. This noninvasive sampling method is used to analyze unique tumor components released into the peripheral circulation and allows serial sampling and longitudinal monitoring of tumor progression. Several liquid biopsy biomarkers are being extensively studied and have shown promising results in clinical applications of BC, including early detection, detection of microscopic residual disease, prediction of recurrence, and response to therapy. Therefore, in this review, we aim to provide an update on various novel blood-based liquid biopsy markers and review the advantages and current limitations of liquid biopsy in BC therapy. The role of blood-based circulating tumor cells, circulating tumor DNA, cell-free RNA, exosomes, metabolomics, and proteomics in diagnosis, prognosis, and treatment monitoring, and their applicability to the personalized management of BC, are highlighted.

Abstract Renal cell carcinoma (RCC) is a major pathological type of kidney cancer and is one of the most common malignancies worldwide. The unremarkable symptoms of early stages, proneness to postoperative metastasis or recurrence, and low sensitivity to radiotherapy and chemotherapy pose a challenge for the diagnosis and treatment of RCC. Liquid biopsy is an emerging test that measures patient biomarkers, including circulating tumor cells, cell-free DNA/cell-free tumor DNA, cell-free RNA, exosomes, and tumor-derived metabolites and proteins. Owing to its non-invasiveness, liquid biopsy enables continuous and real-time collection of patient information for diagnosis, prognostic assessment, treatment monitoring, and response evaluation. Therefore, the selection of appropriate biomarkers for liquid biopsy is crucial for identifying high-risk patients, developing personalized therapeutic plans, and practicing precision medicine. In recent years, owing to the rapid development and iteration of extraction and analysis technologies, liquid biopsy has emerged as a low cost, high efficiency, and high accuracy clinical detection method. Here, we comprehensively review liquid biopsy components and their clinical applications over the past 5 years. Additionally, we discuss its limitations and predict its future prospects.

Abstract In recent years, 5-methylcytosine (m5C) RNA modification has emerged as a key player in regulating RNA metabolism and function through coding as well as non-coding RNAs. Accumulating evidence has shown that m5C modulates the stability, translation, transcription, nuclear export, and cleavage of RNAs to mediate cell proliferation, differentiation, apoptosis, stress responses, and other biological functions. In humans, m5C RNA modification is catalyzed by the NOL1/NOP2/sun (NSUN) family and DNA methyltransferase 2 (DNMT2). These RNA modifiers regulate the expression of multiple oncogenes such as fizzy-related-1, forkhead box protein C2, Grb associated-binding protein 2, and TEA domain transcription factor 1, facilitating the pathogenesis and progression of cancers. Furthermore, the aberrant expression of methyltransferases have been identified in various cancers and used to predict the prognosis of patients. In this review, we present a comprehensive overview of m5C RNA methyltransferases. We specifically highlight the potential mechanism of action of m5C in cancer. Finally, we discuss the prospect of m5C-relative studies.

Abstract Background Biochemical recurrence (BCR) after initial treatment, such as radical prostatectomy, is the most frequently adopted prognostic factor for patients who suffer from prostate cancer (PCa). In this study, we aimed to construct a prognostic model consisting of gene expression profiles to predict BCR-free survival. Methods We analyzed 70 metabolic pathways in 152 normal prostate samples and 494 PCa samples from the UCSC Xena dataset (training set) via gene set enrichment analysis (GSEA) to select BCR-related genes and constructed a BCR-related gene risk score (RS) model. We tested the power of our model using Kaplan–Meier (K–M) plots and receiver operator characteristic (ROC) curves. We performed univariate and multivariate analyses of RS using other clinicopathological features and established a nomogram model, which has stronger prediction ability. We used GSE70770 and DFKZ 2018 datasets to validate the results. Finally, we performed differential expression and quantitative real-time polymerase chain reaction analyses of the UCSC data for further verification of the findings. Results A total of 194 core enriched genes were obtained through GSEA, among which 16 BCR-related genes were selected and a three-gene RS model based on the expression levels of CA14, LRAT, and MGAT5B was constructed. The outcomes of the K–M plots and ROC curves verified the accuracy of the RS model. We identified the Gleason score, pathologic T stage, and RS model as independent predictors through univariate and multivariate Cox analyses and constructed a nomogram model that presented better predictability than the RS model. The outcomes of the validation set were consistent with those of the training set. Finally, the results of differential expression analyses support the effectiveness of our model. Conclusion We constructed an RS model based on metabolic genes that could predict the prognosis of PCa patients. The model can be easily used in clinical applications and provide important insights into future research on the underlying mechanism of PCa.

Objectives Most kidney stones contain calcium, which is closely associated with human bone health. Therefore, we aimed to determine the relationship between the history of kidney stones and human bone health. This study examined the associations between lumbar bone mineral density (BMD), serum 25-hydroxyvitamin D (25-OHD) and a history of kidney stones in individuals aged between 30 years and 69 years.Design and data analysis A multivariate logistic regression model was used to estimate the relationship between lumbar BMD, serum 25-OHD levels and kidney stones in this cross-sectional study. All models incorporated survey sample weights and were adjusted for covariates.Setting National Health and Nutrition Examination Survey (NHANES) 2011–2018. The exposure and outcomes of this study included the lumbar BMD and presence of kidney stones.Participants All the 7500 participants for this cross-sectional survey were selected from the NHANES between 2011 and 2018.Main outcome measures The main outcome of this study was the presence of kidney stones. The interviewers asked the questions on kidney stones while the respondents were at home, using a computer-assisted personal interview system.Results Lumbar BMD was negatively correlated with a history of kidney stones in all three multivariate linear regression models; the negative association existed in all genders after adjusting for all confounding factors. In the multiple regression analysis, there was an interaction between serum 25-OHD and lumbar BMD (p

Machine learning (ML) is an innovative method that is widely used in data prediction. Predicting the COVID-19 distribution using ML is essential for urban security risk assessment and governance. This study uses conditional generative adversarial network (CGAN) to construct a method to predict the COVID-19 hotspot distribution through urban texture and business formats and establishes a relationship between urban elements and COVID-19 so that machines can automatically predict the epidemic hotspots in cities. Taking Macau as an example, this method is used to determine the correlation between the urban texture and business hotspots of Macau and the new epidemic hotspot clusters. Different types of samples afforded different epidemic prediction accuracies. The results show the following: (1) CGAN can accurately predict the distribution area of COVID-19, and the accuracy can exceed 70%. (2) The results of predicting the COVID-19 distribution through urban texture and POI data of hospitals and stations are the best, with an accuracy of more than 60% in experiments in different regions of Macau. (3) The proposed method can also predict other areas in the city that may be at risk of COVID-19 and help urban epidemic prevention and control.

The electrohydrodynamic direct-writing (EDW) technology has been widely used in the integration of micro-/nano-systems. However, the complex model is a critical obstacle for the uniformity and controllability of the EDW fiber. It is difficult to gain an appropriate control strategy for position accuracy and the industrial application of EDW technology. Fuzzy control has a significant effect on objects in which the mathematical models are complex and the dynamic characteristics are difficult to capture. In this paper, the integrated fuzzy control method based on the jet mode and the electrospinning current was designed for the EDW system, and four groups of experiments were set up in different control schemes: the open-loop control, the current control, the jet mode control, and the integrated control. With the integrated control, the volatility percentage of the fiber spacing decreased from 23% to 9.7%, and the volatility percentage of the electrospinning current decreased from 35% to 14%. The fuzzy control shows dramatic effects on the uniformity and the deposition precision of the EDW fibers, which will extend the fields of application of EDW.

Objective We aimed to construct and validate nomograms to predict overall survival (OS) and cancer-specific survival (CSS) for patients with chromophobe renal cell carcinoma (chRCC) after nephrectomy.Design This study is a retrospective cohort study.Setting and participants There were 2810 patients with chRCC from Surveillance, Epidemiology and End Results database diagnosed between 2010 and 2015 included in the study who were randomly divided into a training cohort (n=1970) and a validation cohort (n=840). Another single-centre external validation cohort containing 124 patients from our hospital was also involved in our study.Primary and secondary outcome measures OS and CSS.Results Nomograms for OS and CSS include four and five variables, respectively, from the result of least absolute shrinkage and selection operator regression analyses. Nomograms reveal the accurate discrimination by the area under the curve of receiver operating characteristic (ROC) curves and C-indexes, with a C-index value of 0.777 (95% CI 0.728 to 0.826), 0.810 (95% CI 0.747 to 0.873) and 0.863 (95% CI 0.773 to 0.953) for the training cohort, the internal validation cohort and the external validation cohort in the nomogram for OS; and a C-index value of 0.884 (95% CI 0.829 to 0.939), 0.868 (95% CI 0.772 to 0.964) and 0.862 (95% CI 0.760 to 0.964) for the training cohort, the internal validation cohort and the external validation cohort in the nomogram for CSS. It was also proven that there was a high degree of conformance between the predicted and observation results by calibration plots. In addition, the comparison of ROC curves and C-indexes between nomograms and seventh tumour, node and metastasis stage demonstrated that nomograms were better in accuracy and efficacy ability.Conclusions We successfully constructed two accurate and effective nomograms to predict OS and CSS for patients with chRCC after nephrectomy, which can help clinical doctors choose individual treatment strategies for chRCC patients.

The COVID-19 epidemic has become a global challenge, and the urban wind environment, as an important part of urban spaces, may play a key role in the spread of the virus. Therefore, an in-depth understanding of the impact of urban wind environments on the spread of COVID-19 is of great significance for formulating effective prevention and control strategies. This paper adopts the conditional generative confrontation network (CGAN) method, uses simulated urban wind environment data and COVID-19 distribution data for machine training, and trains a model to predict the distribution probability of COVID-19 under different wind environments. Through the application of this model, the relationship between the urban wind environment and the spread of COVID-19 can be studied in depth. This study found that: (1) there are significant differences in the different types of wind environments and COVID-19, and areas with high building density are more susceptible to COVID-19 hotspots; (2) the distribution of COVID-19 hotspots in building complexes and the characteristics of the building itself are correlated; and (3) similarly, the building area influences the spread of COVID-19. In response to long COVID-19 or residential area planning in the post-epidemic era, three principles can be considered for high-density cities such as Macau: building houses on the northeast side of the mountain; making residential building layouts of “strip” or “rectangular” design; and ensuring that the long side of the building faces southeast (the windward side). (4) It is recommended that the overall wind speed around the building be greater than 2.91 m/s, and the optimal wind speed is between 4.85 and 8.73 m/s. This finding provides valuable information for urban planning and public health departments to help formulate more effective epidemic prevention and control strategies. This study uses machine learning methods to reveal the impact of urban wind environments on the distribution of COVID-19 and provides important insights into urban planning and public health strategy development.

In recent years, methylation modification regulators have been found to have essential roles in various tumor mechanisms. However, the relationships between N6-methyladenosine (m6A) and 5-methylcytosine (m5C) regulators and clear cell renal cell carcinoma (ccRCC) remain unknown. This study investigated these relationships using the data from The Cancer Genome Atlas database. We calculated risk scores using a Lasso regression analysis and divided the patient samples into two risk groups (tumor vs. normal tissues). Furthermore, we used univariate and multivariate Cox analyses to determine independent prognostic indicators and explore correlations between the regulatory factors and immune infiltrating cell characteristics. Finally, quantitative reverse transcriptase–polymerase chain reaction (PCR) and The Human Protein Atlas were used to verify signature-related gene expression in clinical samples. We identified expression differences in 35 regulatory factors between the tumor and normal tissue groups. Next, we constructed a five-gene risk score signature (NOP2 nucleolar protein [NOP2], methyltransferase 14, N6-adenosine-methyltransferase subunit [METTL14], NOP2/Sun RNA methyltransferase 5 [NSUN5], heterogeneous nuclear ribonucleoprotein A2/B1 [HNRNPA2B1], and zinc finger CCCH-type containing 13 [ZC3H13]) using the screening criteria (p < 0.01), and then divided the cases into high- and low-risk groups based on their median risk score. We also screened for independent prognostic factors related to age, tumor grade, and risk score. Furthermore, we constructed a Norman diagram prognostic model by combining two clinicopathological characteristics, which demonstrated good prediction efficiency with prognostic markers. Then, we used a single-sample gene set enrichment analysis and the cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) method to evaluate the tumor microenvironment of the regulatory factor prognostic characteristics. Moreover, we evaluated five risk subgroups with different genetic signatures for personalized prognoses. Finally, we analyzed the immunotherapy and immune infiltration response and demonstrated that the high-risk group was more sensitive to immunotherapy than the low-risk group. The PCR results showed that NSUN5 and HNRNPA2B1 expression was higher in tumor tissues than in normal tissues. In conclusion, we identified five m6A and m5C regulatory factors that might be promising biomarkers for future research.

ObjectiveTo evaluate the association between perioperative estimated glomerular filtration rate (eGFR) and postoperative oncological outcomes in patients with upper tract urothelial carcinoma (UTUC) treated with radical nephroureterectomy (RNU),and to evaluate the effect of sex on this association.MethodsThe medical records of patients with UTUC who underwent RNU between January 2012 and December 2017 at our hospital were retrospectively reviewed. Patients were divided into three groups based on preoperative eGFRs: normal eGFR (>60 mL/min/1.73 m2; n = 179), moderately reduced eGFR (45–60 mL/min/1.73 m2; n = 45), and severely reduced eGFR (≤ 45 mL/min/1.73 m2; n = 36). Statistical analyses were performed to evaluate the prognostic impact of preoperative eGFR on prognosis.ResultsPatient mean age was 66.7 ± 9.6 years, and 47.9% were female. Multivariate regression analysis based on Cox proportional risk models and Kaplan-Meier survival rates showed that lower preoperative eGFR was associated with decreased OS, PFS, and CSS. In the adjusted Cox regression model, patients with normal and moderately reduced eGFRs had a decreased hazard for mortality, with adjusted hazard ratios of 0.13 [95% confidence interval (CI): 0.07–0.26] and 0.36 (95% CI: 0.18–0.73), respectively (P < 0.001). The smooth fitting curve suggested a linear relationship between eGFR and prognostic survival. Additionally, sensitivity subgroup analyses verified an inverse relationship between the reduced eGFR and OS. Women had a lower eGFR and worse oncological outcomes than men. A nomogram for OS was developed based on multivariate analysis with a C-index of 0.754 (95% CI: 0.728–0.779).ConclusionPreoperative renal insufficiency is strongly associated with a higher risk of cancer progression and a lower survival probability. It is important to identify preoperative renal insufficiency in patients with UTUC, particularly female patients.

As a result of environmental and human influences, several types of surface deterioration emerge on historic buildings, resulting in a decline in the quality of these structures and even threats to their safety. In the conventional approach, assessing the surface damage on a structure involves the time-consuming and labor-intensive judgment and evaluation of trained professionals. In this study, it is suggested that the YOLOv4 machine learning model be used to automatically find five types of damage to historical gray-brick buildings. This would make the job go more quickly. This study uses the gray-brick wall buildings in the buffer zone of the global cultural heritage in Macau as an example. In total, 1355 photographs were taken on-site of the gray-brick walls, and the five most common types of damage were identified. By slicing and labeling the photos, a training set of 1000 images was created, and through 200-generation model training, the model can accurately identify and effectively identify the damage state of the gray bricks and enhance the quality judgment and evaluation of the exterior walls of historical buildings. Experiments allow us to reach the following conclusions: (1) The damage to the gray-brick ancient buildings in Macau is affected by the subtropical maritime climate. Missing paint, stains, and cracks are the main contributors to gray-brick wall damage. (2) Machine learning can help determine the type of damage to old gray-brick buildings, which is useful for managing and protecting historical buildings. (3) The model in this study can identify five types of damage: missing, cracking, plant or microbial erosion, yellowing, and pollution on the exterior walls of ancient gray-brick buildings. It is helpful to accurately identify and evaluate the damaged condition of the gray-brick wall and formulate corresponding protection schemes.

Testosterone has been demonstrated to antagonize doxorubicin-induced cardiomyocyte senescence. However, whether testosterone prevents the paraquat-induced cardiomyocyte senescence is largely unknown. The detection of SA-β-gal activity was performed using senescence β-gal staining kit and the reactive oxygen species levels were determined by reactive oxygen species assay kit. The plasmids for insulin-like growth factor 1 shRNA (sh-mIGF-1), sirtuin-1 shRNA (sh-SIRT1), scramble shRNA (sh-NC), overexpressing mIGF-1 (mIGF-1), overexpressing SIRT1 (SIRT1), and negative controls (NC) were obtained for this study. The expression of target genes was detected using quantitative real-time PCR, immunolabeling, and western blot. We found that testosterone significantly delayed the paraquat-induced HL-1 cardiomyocyte senescence as evidenced by decreasing senescence-associated β-galactosidase activity and reactive oxygen species generation, which were accompanied by the up-regulated expression of mIGF-1 and SIRT1. RNA interference to reduce mIGF-1 and SIRT1 expression showed that testosterone prevented paraquat-induced HL-1 senescence via the mIGF-1/SIRT1 signaling pathway. Furthermore, myocardial contraction was evaluated by expression of genes of the contractile proteins/enzymes, such as α-myosin heavy chain 6 (MHC6), α-myosin heavy chain 7 (MHC7), α-skeletal actin (ACTA-1), and sarco/endoplasmic reticulum calcium ATPase-2 (SERCA2). Testosterone adjusted the above four gene expressions and the adjustment was blocked by mIGF-1 or SIRT1 inhibition. Our findings suggested that the mIGF-1/SIRT1 signaling pathway mediated the protective function of testosterone against the HL-1 cardiomyocyte senescence by paraquat, which provided new clues for the mechanisms underlying the anti-aging role of testosterone in cardiomyocytes.

The uniform, rapid, and steady multi-jetting of nanofibers is the key to applying electrospinning technology in mass production. This paper aims to study an air-assisted multi-jet electrospinning method with a curvedly arranged multi-spinneret that can steadily and continuously produce nanofibers. An electrospinning device with a multi-spinneret which utilizes air flow to stretch and constrain jets is developed. The spinnerets are curvedly arranged in a 5 × 5 array, which can reduce the electric field interference between them. The air flow is guided through the gas hood and evenly distributed around each spinneret to form sheath layers, which mitigates the electric field interference between the spinnerets by reducing surface charge density of the jets and which stretches and constrains the jet, improving jetting stability and continuity. The influences of the electric field strength and the collection distance on jet ejection and deposition behavior are studied, and the influence of auxiliary air pressure on jet ejection initiation is also analyzed. The results show that the critical voltage of jet ejection of the central spinnerets is reduced from 8.2 kV to 3.4 kV when the auxiliary air pressure is increased from 0 kPa to 50 kPa, that of the inner spinnerets is reduced from 9.1 kV to 4.0 kV, and that of the outer spinnerets is reduced from 13.1 kV to 5.2 kV. The critical voltage of the outer spinnerets is higher than that of the inner spinnerets, and the critical voltage of the spinnerets in the center is the lowest. The design and development of the multi-spinneret curvedly arranged in a 5 × 5 array and the introduction of sheath air flow provide an effective means for uniform, rapid, and steady multi-jetting of nanofibers, which is beneficial in promoting the use of electrospinning technology in mass production applications.

By introducing image recognition and micro-current testing, jet behavior research was conducted, in which the real-time recognition of ejection mode was realized. To study the factors influencing ejection modes and the current variation trends under different modes, an Electrohydrodynamic Direct-Write (EDW) system with functions of current detection and ejection mode recognition was firstly built. Then a program was developed to recognize the jet modes. As the voltage applied to the metal tip increased, four jet ejection modes in EDW occurred: droplet ejection mode, Taylor cone ejection mode, retractive ejection mode and forked ejection mode. In this work, the corresponding relationship between the ejection modes and the effect on fiber deposition as well as current was studied. The real-time identification of ejection mode and detection of electrospinning current was realized. The results in this paper are contributed to enhancing the ejection stability, providing a good technical basis to produce continuous uniform nanofibers controllably.

The online recognition of jet mode is important for the accurate control and further application of electrohydrodynamic direct-writing (EDW) technology. An EDW system with a current detection module is built for jet mode recognition. The current of the EDW jet is measured to recognize the jet mode when printing patterned structures. Then, a data processing program with a digital Kaiser low-pass filter is developed in MATLAB, via which the noise of the current signal is reduced. The features of EDW current, including the current fluctuation and the peak current intervals, are studied to recognize different jet modes. The current characteristics of three jet modes are investigated: droplet ejection mode, Taylor cone ejection mode, and retractive ejection mode. The Taylor cone ejection mode has the smallest coefficient of variation of peak current. This work provides a good way of designing the optimized control algorithm and of realizing the closed-loop control system, which contributes to enhancing the jet stability and accelerating the application of EDW technology.

Laminar sheath gas is introduced to increase the stability of Electrohydrodynamic Direct-Writing (EDW). The external stretching force from sheath gas promotes the ejection threshold, the diameter of jet and printed fibers as well. The critical voltage decreases with the increase of sheath gas pressure. The stretching force from sheath gas decreases the diameter of printed fiber as well as that of charged jet. As sheath gas pressure increases from 0 to 25 kPa, the average diameter of micro/nano structure reduces from 4.46μm to 845.25 nm. The laminar field flow of sheath gas shelters the charged jet free from the surrounding interferences, and helps charged jet to move in a straight line. With the help of sheath gas, the stability of charged jet can be improved to direct-write precise complex micro-pattern. The position precision of direct-written pattern is less than 5μm. As a novel method, EDW with laminar sheath gas would promote the deposition precision of printed micro/nano structure and its application.

Electrospinning has been widely used in fabricating nanofibers and nanofibrous membranes. Recently, the fabrication of three-dimensional (3D) nanofibrous macrostructures has become a hot subject in the development of electrospinning technology. In this paper, the 3D nanofibrous macrostructure was constructed by using electrospinning apparatus with both dynamic and static 3D collecting templates. The effect of the governing parameters on the formation process of 3D macrostructure is studied, such as the applied voltage, the flow rate, the needle-tip-to-collector distance, and the rotating speed. It was found that laying the collecting device either in parallel or perpendicularly with some gap in between, would lead to orderly deposition of nanofibers. In this study, a “dumbbell” dynamic collector was used to fabricate special 3D macrostructures consisting of multilayers of fibrous membranes. By adjusting the rotating speed of the collector, the formation process of multilayer 3D macrostructure can be controlled. An umbrella-shaped static structure collector was used to fabricate 3D framework structures. It is feasible to fabricate various 3D nanofibrous structures via electrospinning with 3D collecting templates, which has great potential in tissue engineering.