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Volumetric error and dynamic error are the main error sources that lead to position deviation of the cutting tool relative to the workpiece in five-axis machine tools. To comprehensively evaluate the positioning performance of the five-axis machine tools, this paper presents a comprehensive approach to identify both the volumetric and dynamic errors. A group of circular trajectories for a double ball-bar device is designed and performed in the measurement procedure. The volumetric performance is firstly evaluated by calculating the shape deviation between the real and designed circular trajectories. Since geometric errors are the main error source of volumetric inaccuracy, a position-independent geometric error (also named as location error) is identified from the measurement data in this work. A least square method–based algorithm is formulated to calculate the squareness errors between the three linear axes and the location errors of the two rotary axes. To evaluate the dynamic performance, the tangential and normal deviations between the real and designed circular trajectories are monitored. Particularly, as the magnitude of dynamic error has a strong correlation with the feedrate, the circular tests are repeated at three different feedrates. The experimental study is conducted on a five-axis machine tool to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In addition to their many well-known advantages (e.g., ultra-high porosity, good pore size distribution, easy functionalization, and structural tolerability), metal-organic frameworks (MOFs) are a new class of advanced functional materials. However, their backbones are highly susceptible to deformation after exposure to acidic or alkaline conditions. As a result of lithium-ion batteries embedding or detaching directly from MOFs, they irreversibly collapse. As a result, they fail to maintain their electrochemical performance. These factors have hindered the development of MOFs as direct electrode materials, making the design of MOF materials with controlled morphology and stable dimensions a new challenge. In this study, we adopted a versatile and effective method to synthesize a novel MOF material (NiCo-BP (BP = BTC/phen and BTC = 1,3,5-benzenetricarboxylic acid)) using the rigid ligands 1,10-phenanthroline and homobenzotrizoic acid, and the emergence of the Ni–O/N and Co–O/N coordination layers was observed by extended X-ray absorption fine structure (EXAFS) tests, indicating that Ni and Co were coordinated with heterocyclic N-given atoms to form a stable p–π conjugated structure. Meanwhile, the metal-ion is attached to the carboxylic acid ligand on the other side, making the metal-organic skeleton complete and robust. The nanosphere structure of NiCo-BP (∼ 400 nm) allows for full exposure and utilisation of the active sites, especially the Ni, Co, and phenanthroline units, and exhibit impressively high specific capacity and cycling stability. At a high current density of 1.0 A·g−1, a high discharge specific capacity of 631.6 mAh·g−1 was obtained after 1000 cycles. The co-participation of two organic ligands in the coordination is in accordance with the theory of soft and hard acids and bases, which contributes to the ability of the material to maintain a high capacity in cycling as well as its cyclic stability. [ABSTRACT FROM AUTHOR]

According to ISO 230-3, the linear axis includes six thermal error motions. Measuring and modeling multi-position full-term thermal errors in linear axis are challenging and essential since they are position-dependent and time-varying. This study presents for the first time a method for modeling and predicting the full-term thermal error of linear axis with multi-positions. Firstly, the full-term thermal error of the linear axis was measured in real-time. The nonlinearity and time delay of the thermal deformation of the screw are analyzed based on the heat transfer theory. Then, a multidimensional spatio-temporal graph convolution-attention mechanism (MSTGCN-A) model is proposed to model the full-term thermal error at multi-positions on the linear axis. The model adaptively learns the adjacency relationship of nodes and fuses the spatial information of temperature points without screening temperature-sensitive points. GRU-CNN, MTCN-A, and BiLSTM-CNN are also used as comparative models to verify the accuracy of the models. Under varying operating conditions, the proposed model outperforms the comparative model that requires temperature-sensitive point selection. [ABSTRACT FROM AUTHOR]

The accuracy of material extrusion-based 3D printers is greatly affected by the high temperature in the chamber due to the thermal-induced deformation of components. However, most existing measurement equipment cannot be applied to high-temperature environments, which hinders the corresponding error measurement. To address this issue, a geometric error detection system and identification algorithm based on binocular vision are proposed. Firstly, a corner detection algorithm and a ray-intersection binocular model are used to identify the three-dimensional displacement of the target. Secondly, an error separation and identification algorithm is proposed to identify 21 position-dependent geometric errors. Error measurement experiments are conducted on a 3D printer at room temperature and high temperature, respectively. The experimental results at room temperature are verified using a double-ball bar. Finally, an error compensation experiment is conducted to verify the effectiveness of error identification, which also shows the contribution of error motions of linear axes on the printing accuracy. [ABSTRACT FROM AUTHOR]

In ultra-precision diamond turning, the reduction of machining form errors can generally be achieved through on-machine measurement and compensation. However, the efficiency of conventional compensation methods is often insufficient, particularly when high form accuracy is required or when intricate surface topography and microstructures need to be machined. Consequently, this research proposes a novel machining error compensation method based on iterative learning from on-machine measured data to enhance the machining accuracy and compensation efficiency. The on-machine measurement system and cutting path generation algorithm are introduced first. Then, the compensation method via iterative learning is presented theoretically, demonstrating a higher convergence order compared to the conventional method. Finally, machining experiments involving the cutting of cosine surfaces are conducted, followed by measurements of the processed workpieces. The experimental results indicate that after four rounds of compensation using the conventional method, the peak-to-valley (PV) value of the form error is reduced to 0.1134 μ m . In contrast, employing the proposed method, a similar value of 0.1156 μ m is achieved after only two rounds of compensation. This highlights the significant reduction in compensation time facilitated by the proposed method. Furthermore, the measurement results verify that the proposed compensation method maintains excellent surface quality. [ABSTRACT FROM AUTHOR]

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B-spline curve approximation is widely used for fitting linear toolpaths to improve machining quality and efficiency in CNC machining. For a high-quality smoothing method, the control of both approximation error and curve curvature needs to be taken into account. To reduce the maximum curve curvature while meeting the precision requirements, a B-spline approximation scheme with tool tip position adjustment is proposed in this paper. Toolpaths are first divided into several subdivisions according to the discrete curvature of each tool tip point. For subdivisions that need adjustment, tool tip positions are adjusted to minimize the maximum discrete curvature. An existing approximation method named energy-term-incorporated progressive and iterative approximation for least square fitting (ELSPIA) is selected and improved to fit the adjusted toolpaths and lower the chord errors. For improving the numerical stability of the ELSPIA method, the way of searching appropriate foot point parameters is discussed in this paper. Deviation expansion factors of tooltip points are also defined to make the ELSPIA method suitable for fitting the adjusted toolpaths. Both simulations and experimental studies are conducted to prove that the proposed method can significantly decrease the maximum curvature of fitted B-spline curves and improve the machining efficiency without exceeding the tolerance. For example, experimental results show that for the tested butterfly and rabbit toolpaths, the proposed method can improve the machining efficiency by 2.61% and 2.37%, compared with the ELSPIA method without tool tip position adjustment. [ABSTRACT FROM AUTHOR]

Background: Lacrimal adenoid cystic carcinoma (LACC) is the most common orbital malignant epithelial neoplasm. LACC with high-grade transformation (LACC-HGT) has higher rates of recurrence, metastasis, and mortality than LACC without HGT. This study investigated the effects of microRNA-29a-3p (miR-29a-3p) in the pathogenesis of LACC-HGT. Methods: An Agilent human miRNA microarray was used to screen the differentially expressed miRNAs (DEMs) in LACC and LACC-HGT tumor tissues. Then, the primary cells obtained in previous studies were used to determine the effect of miR-29a-3p. Results: The expression of miR-29a-3p was abnormally lower in LACC-HGT than in LACC. miR-29a-3p can specifically target the 3ʹ UTR of Quaking mRNA and down-regulate Quaking expression, thereby inhibiting the proliferation, migration, and epithelial–mesenchymal transition of LACC cells. Conclusions: This study illustrated that miR-29a-3p functions as a tumor suppressor by down-regulating the expression of Quaking to inhibit the tumorigenesis of LACC cells. This study may also reveal the pathogenesis of HGT in LACC cells and provide a reference for LACC-HGT targeted diagnosis. [ABSTRACT FROM AUTHOR]

The traditional blade inspection methods generally suffer from the drawback of low efficiency due to the inefficient measurement motion manner of point-by-point probing. Although the emerging five-axis scanning probing could tremendously boost the inspection efficiency by adopting the advanced probing apparatus, the existing five-axis scanning path generation methods either require an empirical segmentation of the measured surface or totally ignore the interference-free constraint. Thus, they could not be applied to the inspection of impeller blades. This paper proposes an algorithm to automatically generate the interference-free five-axis sweep scanning path for inspection of impeller blades with the considerations of both the interference-free constraint and the geometric characteristics of the blade surface. First, the blade surface is segmented into several simple patches according to the curvature analysis. Then, each surface patch can be re-parameterized by the rectangular conformal mapping and four middle parametric lines are extracted as the candidate guiding curves. The optimal guiding curve is selected from the candidates according to its length and the interference-free constraints. Finally, the sweeping path on each surface patch and the transition path between patches are generated according to the optimal guiding curve. The experiments carried out on a centrifugal impeller and an axial impeller validate the effectiveness of the proposed method. The advantage of the proposed method is also verified by comparing with a leading commercial software ApexBlade, which needs lots of trial-and-error to generate the correct inspection path. [ABSTRACT FROM AUTHOR]

Cardiopulmonary bypass (CPB) is a crucial technique used to repair congenital heart defects (CHD); however, it may induce inflammatory response, leading to airway inflammation and need for prolonged mechanical ventilation. In this study, we aimed to evaluate the effect of budesonide nebulization in children with high serum total immunoglobulin E (tIgE) levels undergoing surgical repair of CHD via CPB. We conducted a randomized, single-center, controlled trial at a tertiary teaching hospital. One-hundred and one children with high tIgE were enrolled and randomized into the budesonide nebulization group (BUD group, n = 50) or the normal saline nebulization group (NS group, n = 51) between January 2020 and December 2020. Budesonide or normal saline was administered through a vibrating mesh nebulizer during mechanical ventilation every 8 h. Blood and bronchoalveolar lavage fluid (BALF) samples were examined and data on airway mechanics and clinical outcomes were recorded. IL-6 and IL-8 levels in the blood and BALF samples significantly increased after CPB in both groups. Budesonide inhalation reduced IL-6 and IL-8 levels in the blood and BALF samples in children with high tIgE (P < 0.05). The mean airway pressure, PCO2, and oxygen index in the BUD group were significantly lower than those in the NS group after the first inhalation dose and persisted until almost 24 h after surgery. The peak inspiratory pressure and drive pressure were lower in the BUD group than in the NS group at nearly 24 h after surgery, with no significant difference at other time points. Additionally, the duration of mechanical ventilation, number of noninvasive ventilations after extubation, and number of patients using aerosol-inhaled bronchodilators after CICU in the BUD group were significantly lower than those in the NS group (P < 0.05). Children with high preoperative tIgE levels are at risk of airway inflammation after cardiopulmonary bypass. Inhaling budesonide during postoperative mechanical ventilation can reduce the intensity of inflammatory reactions, shorten the duration of mechanical ventilation, reduce airway pressure and the utilization of NIV after extubation. [ABSTRACT FROM AUTHOR]

Indocyanine green (ICG) angiography is of great importance for ophthalmic diagnostic applications and is mainly used to check for choroidal vascular diseases. However, ICG fluorescence imaging probes aggregate in water because they have sulfonyl groups and can form dimers and oligomers. This effect thus reduces the fluorescence of the probes. Therefore, we have established a simple and effective way to prepare β-cyclodextrinmodified ICG (ICG–β-CD) via the host–guest assembly process. In contrast to ICG, ICG–β-CD avoided solution aggregation. Moreover, it exhibited improved absorption intensity. When used as an angiographic contrast agent for ophthalmic choroid examination and diagnosis in SD rats, the fluorescence imaging effect of ICG–β-CD on retinal and choroidal vessels was better than that of ICG on choroidal vessels. Therefore, ICG–β-CD is expected to achieve a "two birds with one stone" effect. [ABSTRACT FROM AUTHOR]

A grinding method of fused glass is proposed through the dry chemical modification of atmospheric pressure plasma. Before grinding, the surface of fused glass is chemically modified by atmospheric pressure plasma, then the grinding experiment is carried out without any coolant. The objective is to explore the grinding characteristics of the dry chemically modified grinding by atmospheric pressure plasma. First, the experiment on the dry chemical modification of fused glass was carried out with different parameters of atmospheric pressure plasma. Secondly, a #600 diamond wheel was used to perform the grinding experiment with and without modification. Then, the element content, morphologies, and nanoindentation test of the dry chemically modified surface were investigated with reference to the parameters of atmospheric pressure plasma. Finally, the grinding roughness and morphologies were investigated with reference to the modified degree. It is shown that the modified degree of fused glass is influenced by the flow rate of CF4 and the feed speed of plasma. The mechanical property of material changes with the change of the modified degree, which plays a great influence on grinding processing. The grinding roughness can reduce by 32.7% with modification than one without modification. Moreover, the grinding roughness and morphology are related to the modified degree of fused glass. It is confirmed that the grinding processing of fused glass may be improved through the dry chemical modification of atmospheric pressure plasma. [ABSTRACT FROM AUTHOR]

Summary: Background. Several TRK inhibitors have demonstrated clinical efficacy in patients with solid tumors harboring NTRK gene fusions. However, the natural history and prognostic implications of NTRK fusions in solid tumors remain unknown. Methods. A cohort of 77 MD Anderson Cancer Center patients (MDACC) with NTRK gene fusions was identified and retrospectively compared to a second cohort from the Cancer Genome Atlas (TCGA) database. Due to paucity of events in early stage cancers and lack of TCGA data in rare tumors, 25 randomly selected MDACC patients were matched to 122 TCGA patients without NTRK gene fusion. Next we assessed the associations between NTRK gene fusion and overall (OS) and progression-free survivals (PFS). Results. Among the 77 MDACC patients with NTRK gene fusions, 18 NTRK fusion partners were identified. There were insufficient OS events for analysis in the matched cohort. PFS was not significantly different (p = 0.49) between the NTRK-fusion positive MDACC patients (median PFS 786 weeks, 95% CI 317-NE) and the NTRK-fusion negative TCGA patients (median PFS NE). The adjusted hazard ratio comparing TCGA patients to MDACC patients was HR = 0.72 (95% CI: 0.23–2.33), which trended towards a reduced rate of progression or death experienced by TCGA patients. Conclusions. This study did not identify statistically significant associations between NTRK fusion and PFS. Nonsignificant trends estimated increases in the risk of progression or death events for patients with NTRK fusions when compared to matched controls. Our findings help illuminate the influence of NTRK fusions on the natural history of a variety of solid tumors. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the potential roles of MIR3142HG, a novel long non-coding RNA (lncRNA) in lipopolysaccharide (LPS)-induced acute lung injury (ALI). ALI was simulated by the treatment of LPS in human pulmonary microvascular endothelial cells (HPMECs). The expression of MIR3142HG, miR-450b-5p and high-mobility group box 1 (HMGB1) was determined by real-time PCR and western blotting. Functional analysis was performed through the assessment of cell viability, apoptosis and the production of proinflammatory cytokines. The interactions among MIR3142HG, miR-450b-5p and HMGB1 were analyzed by bioinformatics methods, dual-luciferase reporter and RNA pull-down assays. Using gain- and loss-of-function approaches, the in vitro functions of MIR3142HG and miR-450b-5p were subsequently assessed. MIR3142HG expression was upregulated, while miR-450b-5p was decreased in LPS-treated HPMECs. MIR3142HG knockdown protected against ALI induced by LPS through alleviating the apoptosis and inflammation of HPMECs. MIR3142HG impaired miR-450b-5p-mediated inhibition of HMGB1. Besides, the effects of MIR3142HG silencing could be alleviated by miR-4262 inhibition or HMGB1 overexpression. MIR3142HG mediated LPS-induced injury of HPMECs by targeting miR-450b-5p/HMGB1, suggesting that MIR3142HG might serve as a therapeutic potential for the treatment of ALI. [ABSTRACT FROM AUTHOR]

Background: Elevated arterial–central venous carbon dioxide partial pressure difference (AVCO2) may be an important marker to predict tissue and organ hypoperfusion in adults. We analyzed the hemodynamic data of infants with congenital heart disease who underwent corrective repair with cardiopulmonary bypass (CPB) to identify whether AVCO2 has clinical significance in early postoperative tissue hypoperfusion, occurrence of complications, and clinical outcomes. Methods: Infants with clinical conditions of hypoperfusion, without volume responsiveness and with ineffective initial treatment, within 3 h of cardiac surgery were enrolled in this study. A pulse contour cardiac output catheter was used to monitor the cardiac index (CI). Eight measurements of arterial blood gas and central venous blood gas were taken within 42 h after surgery. Clinical data of all patients were recorded. Results: A total of 69 children were enrolled in this study. Arteriovenous oxygen difference, AVCO2, lactic acid level, and vasoactive inotropic score in the hypoperfusion group (oxygen supply/oxygen consumption ratio [DO2/VO2] of ≤ 2) were significantly higher than those in the non-hypoperfusion group (DO2/VO2 > 2), while the CI in the hypoperfusion group was significantly lower than that in the non-hypoperfusion group. The cutoff value of AVCO2 to predict DO2/VO2 ≤ 2 was 12.3 within 42 h of surgery with area under the curve of 0.84. High AVCO2 is more likely to be associated with some complications and prolonged mechanical ventilation and length of stay in the intensive care unit. Conclusion: Elevated AVCO2 within 42 h of CPB in infants is associated with tissue and organ hypoperfusion and incidence of complications. Persistent or repeated increase in AVCO2 indicates poor prognosis. [ABSTRACT FROM AUTHOR]

Purpose: The aim of our study was to evaluate the relationship between the 24-h blood pressure (BP) profile, plasma NT-proBNP levels and left ventricular hypertrophy (LVH) in subjects with primary aldosteronism (PA) compared to patients with essential hypertension (EH). Methods: A total of 385 consecutive patients with PA [187 with aldosterone producing adenoma (APA) and 198 with idiopathic hyperaldosteronism (IHA)] and 385 patients with EH were matched based on age, sex, body mass index (BMI), BP values and duration of hypertension. Twenty-four-hour ambulatory BP monitoring (ABPM), plasma levels of NT-proBNP, left ventricular mass index (LVMI), and other clinical medical data were assessed in all patients. Results: No differences in age, sex, BMI, clinical BP, 24-h mean BP, daytime BP, or duration of hypertension were found between groups. Nighttime systolic BP (130 ± 16 vs. 127 ± 17 mmHg, p < 0.05) and diastolic BP (82 ± 10 vs. 79 ± 11 mmHg, p < 0.01) were higher in PA patients than in EH patients. In addition, nocturnal BP decline was reduced, while median NT-proBNP (53.7 vs. 33.2 pg/ml, P < 0.001) and LVMI (113 ± 25 vs. 102 ± 26 g/m2, P < 0.001) were higher in PA patients than in EH patients. Moreover, the median NT-proBNP level was higher in APA patients than in IHA patients (68.0 vs. 42.4 pg/ml, P < 0.001). In stepwise multivariate regression analysis, LVMI was correlated with NT-proBNP, nighttime systolic BP and sex in PA patients. Conclusions: Patients with PA show higher nighttime BP and NT-proBNP levels and lower nocturnal BP decline than those with EH. In addition, higher nocturnal systolic BP has been shown to be strongly associated with cardiac damage in PA patients. [ABSTRACT FROM AUTHOR]

Typically, the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first, lightly-damped resonance. To overcome this issue, a variety of open- and closed-loop control techniques that commonly combine damping and tracking actions, have been reported in literature. However, in almost all these cases, the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis. Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth. However, such a shift typically entails a major mechanical redesign of the nanopositioner. The integral resonant control (IRC) has been reported earlier to demonstrate the significant performance enhancement, robustness to parameter uncertainty, guaranteed stability and design flexibility it affords. To further exploit the IRC scheme's capabilities, this paper presents a method of actively shifting the resonant frequency of a nanopositioner's axis, thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme. The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy. And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response. Experiments are conducted on a nanopositioner's axis with an open-loop resonance at 508 Hz. It is shown that by employing the active resonance shifting, the closed-loop positioning bandwidth is increased from 73 to 576 Hz. Consequently, the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%. [ABSTRACT FROM AUTHOR]

A series of novel N-doped carbon-coated Li3V2(PO4)3 (LVPC/N) composites were synthesized by rheological phase method with melamine as nitrogen source. The results showed that N-doping did not affect the main structure of Li3V2(PO4)3/C (LVPC) but only changed the structure and properties of the coating layer, which effectively improved the structural stability and electrochemical performance of LVPC. When the ratio of citric acid to melamine was 5:3, the properties of LVPCN composite were the best. The initial discharge specific capacity was 195 mAh g−1 at 30 mA g−1 in the voltage range of 3.0–4.8 V. After 100 cycles of charge and discharge, the discharge capacity was still 165 mAh g−1, and the capacity retention rate was increased to 85%. Owing to the low cost, high initial discharge capacity, and long lifespan, we believe that the LVPC/N composite is significantly competitive to other cathode materials for application in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Multi-link cable-driven robots (MCDRs) have potential advantages in confined spaces exploration because of their redundancy and flexibility. Operational space wrench and acceleration capability analysis of MCDRs is important for their design, manipulability optimization, and motion planning. However, existing works mainly focus on capability analysis in the joint space. In this paper, we present a zonotope-based iterative method and a simplified capability zonotope to analyze the operational-space wrench and acceleration capability of MCDRs. In the iterative method, the capability generated by some cables can be iteratively added to the initial capability zonotope based on the Minkowski sum. In the simplified zonotope capability representation, a threshold is put forward to reduce redundant vertices and faces with little volume loss. Finally, simulations on a 24 DOFs MCDR are performed to verify the effectiveness of the developed method. The results demonstrate that our iterative algorithm can easily generate the capability zonotope with a few MB ROM, while traditional operational wrench capability evaluation without our iterative algorithm needs 18432 GB ROM. Furthermore, our simplified representation reduces the vertices and faces from 1260 and 2516 to 88 and 172, respectively, but with only 3.3% volume loss, which decreases the constraints of the robot and is conducive to manipulability optimization and motion planning. [ABSTRACT FROM AUTHOR]

Motivated by the sparse literature on succession dynamics in China and other transitional markets we consider the effects of initiating an intra-family leadership succession on firm strategic change and performance on a sample of publicly listed family firms from China. Grounded in upper echelons theory we find that the initiation of a succession process leads to significant strategic change. Based on generational differences between founders and successors we find the succession-strategic change relationship is positively moderated by a successor's international education. We also consider the strategic change to performance relationship. [ABSTRACT FROM AUTHOR]

Lung biopsy is the gold standard for evaluating pathological changes in the pulmonary vascular bed. Knowing the distribution characteristics of pulmonary vascular lesions can improve the accuracy of lung biopsy. To investigate the distribution characteristics of pulmonary vascular remodeling, a reliable porcine model of shunt-associated pulmonary arterial hypertension (PAH) was established. Twenty piglets were randomly divided into the experimental group (n = 10) and the control group (n = 10). A modified Blalock–Taussig shunt (MBTS, left innominate artery to main pulmonary artery) was created surgically in the experimental group. Three months later, an invasive catheter was used to obtain hemodynamic parameters, and lung biopsy was performed to assess the remodeling of pulmonary vascular bed. MBTS was successfully implemented in six piglets. There's no significant difference in hemodynamic parameters of the two groups before the shunt. However, these parameters and right ventricular hypertrophy index of the experimental group were significantly increased after three months shunting. Pathological changes in the experimental group, including thickening of pulmonary artery media, intimal fibrosis, and right ventricular hypertrophy, were observed. Furthermore, the percentage of media thickness and medial area of the experimental group were significantly higher than control group. Histopathology showed that vascular remodeling of the lung was inhomogeneous and that the lateral lesion was more severe than other segments. These results indicated that MBTS could be used to establish a reliable porcine model of shunt-associated PAH and that multisite detection with different segments should be applied to assess the severity of pulmonary vascular remodeling. [ABSTRACT FROM AUTHOR]

While cable-driven snake robots are promising in exploring confined spaces, their hyper-redundancy makes the collision-free motion planning difficult. In this paper, by combining the prediction lookup and interpolation algorithms, we present a new path following method for cable-driven snake robots to high-efficiently slither into complex terrains along a desired path. In our method, we first discretize the desired path into points, and develop the prediction lookup algorithm to efficiently find the points matched with joints of the robot. According to geometric relations between the prediction lookup results and link length of the robot, we develop the interpolation algorithm to reduce the tracking errors caused by the discretization. Finally, simulations and experiments of inspections in two confined spaces including the obstacle array and pipe tank system are performed on our custom-built 25 degree of freedoms (DOFs) cable-driven snake robot. The results demonstrate that the presented method can successfully navigate our snake robot into confined spaces with high computational efficiency and good accuracy, which well verifies effectiveness of our development. [ABSTRACT FROM AUTHOR]

Maximum resultant cutting force control provides a great benefit of improving productivity in machining tasks. This paper presents a new force control method for robot milling that can prevent force overshoots during abrupt part geometry changes. Firstly, the feedrates of the robot at critical cutter locations are optimized offline according to the cutting force model and the part geometry. Secondly, an online parameter self-adaptive proportional-integral (PI) controller is designed in consideration of the robot feed-direction dynamics and the time-varying first-order model of the cutting process. Finally, the offline scheduled feedrates are integrated into the online adaptive controller via a feedforward-like strategy. Experiments demonstrate the effectiveness and advantages of the proposed force control method. [ABSTRACT FROM AUTHOR]

Chatter is a kind of self-excited vibration and causes negative effects in machining processes. This paper presents a practical method to identify the chatter with cutting force signals in milling processes. Since the spectrum of the chatter signal exhibits discrete spectral lines around the chatter frequencies and the Rényi entropy is an effective index to characterize the randomness of data series, the frequency-domain Rényi entropy is proposed as a chatter indicator. As the chatter severity level grows, the signal components at the chatter frequencies become more and more significant, which means a reduction of the randomness of the spectral series. As a result, the value of the Rényi entropy-based indicator decreases rapidly at the onset of the chatter. In order to eliminate the interference of the normal signal components, i.e., the spindle speed-related frequency components, the spectrum is preprocessed to filter out those components first. Various milling experiments are conducted. The results show that the value of the proposed indicator changes sharply at the onset of chatter in various milling conditions with different spindle speeds and cutting depths. Also, the proposed indicator is compared with the commonly used Shannon entropy-based indicator and verified to have a larger difference between the stable and chatter statuses and is higher sensitivity to the chatter. [ABSTRACT FROM AUTHOR]

Mg–11Gd–2Y–xSm–0.6Al (x = 0, 1, 3, 5) alloys were prepared in electromagnetic induction furnace by gas protection. The crystal structure, microstructure and mechanical properties of as-cast Mg–11Gd–2Y–xSm–0.6Al alloys were studied by X-ray diffraction, metallographic microscope, scanning electron microscopy and tensile testing. The results show that the main phases of Mg–11Gd–2Y–xSm–0.6Al alloys are α-Mg matrix, Mg5Gd, Mg24Y5 and Mg41Sm5. The addition of Sm refines the microstructure and increases the number of second phase in the grain boundary. The diffraction peaks of the cylindrical plane (100)α-Mg, base plane (002)α-Mg and conical plane (101)α-Mg are shifted to a low angle. The offset of diffraction peak and the lattice constant of α-Mg increase with the increase in Sm content. The crystal axis ratio decreases with the increase in Sm content. When the addition of Sm is 3%, the ultimate tensile strength reaches to 240 MPa, which increases by 17.07%. The improvement in mechanical properties is mainly attributed to the grain refinement and the decrease in the crystal axis ratio of α-Mg. [ABSTRACT FROM AUTHOR]

Background: Hepatitis B virus (HBV) infection is a public health challenge, especially in China. In clinical practice, HBV infection is associated with nephropathy. Impaired renal function is frequently observed in compensated Chronic Hepatitis B (CHB) and cirrhosis (LC). Thus, renal function must be monitored to avoid nephrotoxic effects before and during nucleoside analog treatment. Investigating the predictive markers of early renal dysfunction is essential. New GFR-predicting equations, based on Pcr and/or CystC, have been recently recommended in the general population, but their performance in liver disease patients has been rarely studied. In this study, we will discuss how to detect renal dysfunction in patients with HBV infection. Methods: A total of 16 LC patients and 23 CHB patients were enrolled in this study, and we collected and compared the clinical data of the two groups. The estimated glomerular filtration rates (eGFRs) were also calculated by several equations. All patients received 99mTc-DTPA dynamic radionuclide imaging examinations to obtain mGFRs as the reference standard. To evaluate the performance of any equation in the CHB and LC groups, paired t test, Pearson's correlation, Kappa analysis and Bland–Altman plots were utilized. Moreover, all 39 subjects were divided into two groups (according to GFR > 90 mL/min/1.73 m2). We compared the serum and urinary markers of kidney injury between the two groups and selected the indicators of renal injury by univariate analysis. Results: The mGFR was 72.26 ± 20.69 mL/min/1.73 m2 in the LC group, and 87.49 ± 25.91 mL/min/1.73 m2 in the CHB group. The paired t test results of eGFR and mGFR showed no difference between eGFR (estimated by the CHINAcr-cys equation) and mGFR (p > 0.05) in the compensated LC and CHB groups. The difference between mGFR and eGFR estimated by other methods was obvious (p < 0.05). Comparing the eGFRs (estimated by 5 different equations) with mGFR in the compensated LC and CHB groups, Pearson's correlation showed that only eGFR (estimated by the CHINAcr-cys equation) had a significant correlation coefficient in CHB (r = 0.678, p = 0.000) and had the highest R2 (R2 = 0.459) among all other measures. The kappa consistency test showed that eGFR from CHINAscr-cys had poor consistency with mGFR in the compensated LC group but moderate consistency in the CHB group. Bland–Altman consistency analysis showed that in the CHB group, the CHINAcr-cys and CKD-EPIcr equations presented narrower acceptable limits than did the aMDRD, c-aMDRD, and CKD-EPIcr-cys equations (62.8, 56.1 vs.85.7, 102.9, 93.6 mL/min per 1.73 m2). In the compensated LC group, the CHINAcr-cys and CKD-EPIcr equations presented narrower acceptable limits than did the aMDRD, c-aMDRD, and CKD-EPIcr-cys equations (83.6, 81.3 vs. 98, 113.5, 106.3 mL/min per 1.73 m2). Serum or urinary markers were compared with renal function (GFR > 90 mL/min/1.73 m2) and showed International normalized ratio (INR) (p = 0.009), creatinine (p = 0.006), urine N-acetyl-β-glucosaminidase (NAG) (p = 0.001) and serum cystatin C (CysC) (p = 0.044). Conclusion: The CHINAcr-cys equation may be more suitable for the estimation of GFR in Chinese patients with CHB or compensated cirrhosis. INR, creatinine, NAG, and CysC are proper biomarkers for screening renal dysfunction in Chinese patients with CHB or compensated LC. [ABSTRACT FROM AUTHOR]

The discontinuity of linear tool path (or G01 blocks) brings about unnecessary feedrate deceleration and fluctuation during machining. To improve the continuity, the linear tool path is usually smoothed by the local transition method or the global fitting method. For micro-line tool path, the transition method will significantly decrease the machining efficiency and introduce feedrate fluctuation. The global fitting method cannot be directly used in the NC interpolation because the indispensable chord error checking and iterative fitting processes are computation-intensive. This paper presents a general, fast and robust B-spline fitting scheme under chord error constraint for high speed interpolation of micro-line tool path. The proposed fitting method guarantees the chord error by utilizing the strong convex hull property of B-spline curves. The knot vector and control points are initially generated by a progressive iterative approximation method and locally refined to conform to the chord error constraint by using an analytical method. The analytical approximation and refining methods avoid solving a linear system of equations that is necessary in the standard B-spline fitting method. The feasibility and efficiency of the proposed scheme has been verified via simulations and experiments. Compared with the traditional fitting method, the proposed scheme can strictly constrain the chord error and can significantly decrease the computational load. Compared with the transition scheme, the proposed scheme can significantly increase the machining efficiency for the same micro-line tool path under the same chord error tolerance. [ABSTRACT FROM AUTHOR]

The micro-structure on hard-brittle chip materials (HBCMs) surface can produce predominant functions and features. The micro-grinding with diamond wheel micro-tip is an efficient method to machine microstructure on HBCMs. However, different HBCMs and crystal orientation may have a significant influence on the micro-grinding performance. In this paper, the micro-grinding performance along different crystal orientation of HBCMs is investigated. First, a dressed 600# diamond grinding wheel is used to micro-grind micro-structure on HBCMs. Then, the experiment of micro-grinding force test is completed. Finally, the quality of microgroove, the grinding ratio and the micro-grinding force are investigated and they are related to the crystal orientation of HBCMs. It is shown that the stronger resistance to the micro-crack propagation has the best quality of microgroove and the smallest grinding ratio. Moreover, the hardest single-crystal SiC has the best machinability and the micro-grinding force is 38.9%, 10.8% and 46.8% less than the one of sapphire, single-crystal Si and quartz glass, respectively. The direction to micro-grind easily is the crystal orientation 〈101¯0〉 for single-crystal SiC and sapphire. In addition, the micro-grinding force increases with the increase of the micro-grinding depth and feed rate and decreases with the increase of the grinding wheel speed. [ABSTRACT FROM AUTHOR]

Development of novel cathode materials for sodium-ion batteries with high capacity and excellent cyclic performance is an exciting and demanding research direction. Herein, we demonstrate the synthesis of NaV3O8 via a rheological phase reaction method. The crystal structure and morphology of synthesized NaV3O8 were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The NaV3O8 powder, calcined at moderate temperature (350 °C) with more uniform and smaller nanorod/nanoplate morphology, and larger d001 spacing, exhibited excellent electrochemical performance as cathode material in sodium ion batteries. A specific discharge capacity of 120 mAh g−1 was achieved at the current density of 120 mA g−1, with exceptional cyclic performance (discharge capacity of 95 mAh g−1 at the 500th cycle). In addition, the NaV3O8 cathode demonstrated excellent rate capability and delivered specific capacity of 80.8 mAh g−1 at current density of 300 mA g−1. The superior electrochemical performance corresponds to the structural stability and faster ionic diffusion. The preliminary results indicate that NaV3O8 can be an alternative cathode material for high-performance sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Pocket milling is widely used in the machining of large thin-walled parts. The remaining wall thickness of the pocket is critical to compromise the weight reduction and the strength, and becomes a crucial dimension requirement during machining. However, the cutting deformation of large thin-walled parts will greatly decrease the accuracy of the remaining wall thickness and needs to be compensated online due to the stochastic characteristics of the deformation. For online compensation methods, the time-delay is usually the critical factor to reduce the control accuracy. The forecasting compensatory control (FCC) provides an effective way to compensate the stochastic errors and solve the time-delay problem. The key of the FCC is the prediction accuracy of the modeling technique. An improved FCC system with an accurate cutting deformation prediction model is developed to guarantee the remaining wall thickness for the pocket milling of a large thin-walled part. The improved FCC system makes use of the advanced online measurement system, the deformation prediction modeling, and the real-time compensation. The proposed prediction model considers the deterministic and stochastic cutting deformations to improve the prediction accuracy. The Kalman filtering is also applied to further enhance the prediction accuracy because of its correctable ability. The cutting simulation and the experiment of machining a rectangular pocket on a large thin-walled plate are both carried out to validate the effectiveness of the proposed method. The accuracy of the remaining wall thickness of the pocket is finally improved. [ABSTRACT FROM AUTHOR]

Based on the idea of collocation methods, a spline-based integration method for the stability prediction of systems governed by time-periodic delay differential equations (DDEs) is presented. A B-spline curve is adopted to approximate the solution of the DDEs using the direct integration technique. The stability of the dynamic system is then predicted using the Floquet theory based on the established state transition matrix. The proposed method can apply to time-periodic DDEs where the delay and the period are incommensurate, and the proposed method is extended to study the stability of milling processes as well. For stability analysis of variable pitch cutters, the proposed method use one or multiple B-spline curves to approximate the solution of the DDEs according to the relationship between the cutter angles and the radial immersion, which can describe exactly the free vibration of the cutter. Compared with the numerical integration method and the Chebyshev collocation method, the simulation results demonstrate that the proposed technique is more efficient and accurate for stability prediction at low radial immersion cases in milling processes with variable pitch cutters. [ABSTRACT FROM AUTHOR]

Peptidic inhibition of the enzyme tyrosinase, responsible for skin pigmentation and food browning, would be extremely useful for the food, cosmetics, and pharmaceutical industries. In order to identify novel inhibitory peptides, a library of short sequence oligopeptides was screened to reveal direct interaction with the tyrosinase. A phage displaying heptapeptide (IQSPHFF) was found to bind most strongly to tyrosinase. The inhibitory activity of the heptapeptide was evaluated using mushroom tyrosinase. The results showed that the peptide inhibited both the monophenolase and diphenolase activities of mushroom tyrosinase with IC values of 1.7 and 4.0 mM, respectively. The heptapeptide is thought to be a reversible competitive inhibitor of diphenolase with the inhibition constants ( Ki) of 0.765 mM. To further investigate how the heptapeptide exerts its inhibitory effect, a docking study between tyrosinase and heptapeptide was performed. The simulation showed that the heptapeptide binds in the active site of the enzyme near the catalytically active Cu ions and forms hydrogen bonds with five histidine residues on the active site. Phage display technology is thus a useful approach for the screening of potential tyrosinase inhibitors and could be widely applicable to a much wider range of enzymes. [ABSTRACT FROM AUTHOR]

We evaluated the effects of different respiratory assist modes on cerebral blood flow (CBF) and arterial oxygenation in single-ventricle patients after bidirectional superior cavopulmonary anastomosis (BCPA). We hypothesized that preserved auto-regulation of respiration during neurally adjusted ventilatory assist (NAVA) may have potential advantages for CBF and pulmonary blood flow regulation after the BCPA procedure. We enrolled 23 patients scheduled for BCPA, who underwent pressure-controlled ventilation (PCV), pressure support ventilation (PSV), and NAVA at two assist levels for all modes in a randomized order. PCV targeting large V (15 mL × kg) resulted in lower CBF and oxygenation compared to targeting low V (10 mL × kg). During PSV and NAVA, ventilation assist levels were titrated to reduce EAdi from baseline by 75 % (high assist) and 50 % (low assist). High assist levels during PSV (PSV) were associated with lower PaCO, PaO, and OSAT, lower CBF, and higher pulsatility index compared with those during NAVA. There were no differences in parameters when using low assist levels, except for slightly greater oxygenation in the NAVA group. Modifying assist levels during NAVA did not influence hemodynamics, cerebral perfusion, or gas exchange. Targeting the larger V during PCV resulted in hyperventilation, did not improve oxygenation, and was accompanied by reduced CBF. Similarly, high assist levels during PSV led to mild hyperventilation, resulting in reduced CBF. NAVA's results were independent of the assist level chosen, causing normalized PaCO, improved oxygenation, and better CBF than did any other mode, with the exception of PSV at low assist levels. [ABSTRACT FROM AUTHOR]

During the machining of sculptured surface, the tool deflection induced by cutting force has a great influence on the shape and dimensional accuracy of the machined components. Previous research attempts on this topic deal with error compensation in three-axis milling process. The purpose of this paper is to provide a novel methodology to compensate these deflections in five-axis ball-end milling of sculptured surface by modifying tool paths. The approach can be implemented in three steps. First, the representation of the five-axis machine configuration and kinematic transformations is given as the basis of the geometry analysis of five-axis milling operations. Second, through the analysis of tool deflection during the five-axis ball-end milling process, the mirror method can be applied to calculate the tool position and orientation. Meanwhile, the compensation reference can be modeled to optimize the tool paths. Finally, all experiments are carried out under the same cutting parameters to prove its effectiveness. The experimental results show effective improvement in the accuracy of the sculptured surface. [ABSTRACT FROM AUTHOR]

Product variation reduction is critical to improve process efficiency and product quality, especially for multistage machining process (MMP). However, due to the variation accumulation and propagation, it becomes quite difficult to predict and reduce product variation for MMP. While the method of statistical process control can be used to control product quality, it is used mainly to monitor the process change rather than to analyze the cause of product variation. In this paper, based on a differential description of the contact kinematics of locators and part surfaces, and the geometric constraints equation defined by the locating scheme, an improved analytical variation propagation model for MMP is presented. In which the influence of both locator position and machining error on part quality is considered while, in traditional model, it usually focuses on datum error and fixture error. Coordinate transformation theory is used to reflect the generation and transmission laws of error in the establishment of the model. The concept of deviation matrix is heavily applied to establish an explicit mapping between the geometric deviation of part and the process error sources. In each machining stage, the part deviation is formulized as three separated components corresponding to three different kinds of error sources, which can be further applied to fault identification and design optimization for complicated machining process. An example part for MMP is given out to validate the effectiveness of the methodology. The experiment results show that the model prediction and the actual measurement match well. This paper provides a method to predict part deviation under the influence of fixture error, datum error and machining error, and it enriches the way of quality prediction for MMP. [ABSTRACT FROM AUTHOR]

The pediatric bone sarcomas osteosarcoma and Ewing sarcoma represent a tremendous challenge for the clinician. Though less common than acute lymphoblastic leukemia or brain tumors, these aggressive cancers account for a disproportionate amount of the cancer morbidity and mortality in children, and have seen few advances in survival in the past decade, despite many large, complicated, and expensive trials of various chemotherapy combinations. To improve the outcomes of children with bone sarcomas, a better understanding of the biology of these cancers is needed, together with informed use of targeted therapies that exploit the unique biology of each disease. Here we summarize the current state of knowledge regarding the contribution of receptor tyrosine kinases, intracellular signaling pathways, bone biology and physiology, the immune system, and the tumor microenvironment in promoting and maintaining the malignant phenotype. These observations are coupled with a review of the therapies that target each of these mechanisms, focusing on recent or ongoing clinical trials if such information is available. It is our hope that, by better understanding the biology of osteosarcoma and Ewing sarcoma, rational combination therapies can be designed and systematically tested, leading to improved outcomes for a group of children who desperately need them. [ABSTRACT FROM AUTHOR]

Rod-like LiVO/carbon composites were successfully prepared by the polymer graphitization of LiVO/polyaniline composites, which were synthesized through the in-situ oxidative polymerization method. The crystal phases of as-prepared samples, confirmed by X-ray diffraction, show that the interlayer spacing in LiVO/carbon composites is much wider than that of the pristine LiVO. Compared to the bare LiVO, the longer and smoother rod-like LiVO/carbon composites, investigated by scanning electron microscope and transmission electron microscope, were covered by a continuously thin layer of fluffy carbon with a thickness of approximate 20 nm. The optimal LiVO/carbon composite delivered a discharge capacity of 219.37 mAh g in the initial cycle, and maintained a high capacity of 263.538 mAh g at the 30th cycle, which was much higher than that of the pristine LiVO (227.645 mAh g). Cyclic voltammetry measurements disclose that, after the carbon coating treatment, the phase transition of the optimal LiVO/carbon composite proceeds more reversibly and smoothly during charging/discharging. The improved cyclability of the optimal LiVO/carbon composite should be attributed to the confinement from thin carbon layer, the structural stability, the good interfacial compatibility, and the well-preserved electrode morphology after prolonged cycles. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The cross-coupled control (CCC) is widely applied to reduce contour errors in contour-following applications. In such situation, the contour error estimation plays an important role. Traditionally, the linear or second-order estimation approach is adopted for biaxial motion systems, whereas only linear approach is available for triaxial systems. In this paper, the second-order contour error estimation, which was presented in our previous work, is utilized to determine the variable CCC gains for motion control systems with three axes. An integrated stable motion control strategy, which combines the feedforward, feedback and CCC controllers, is developed for multiaxis CNC systems. Experimental results on a triaxial platform indicate that the CCC scheme based on the second-order estimation, compared with that based on the linear one, significantly reduces the contour error even in the conditions of high tracking feedrate and small radius of curvature. [ABSTRACT FROM AUTHOR]

In this paper, a novel rate-dependent Prandtl-Ishlinskii (P-I) model is proposed to characterize the rate-dependent hysteresis nonlinearity of piezoelectric actuators. The new model is based on a modified rate-dependent play operator, in which a dynamic envelope function is introduced to replace the input function of the classical play operator. Moreover, a dynamic density function is utilized in the proposed P-I model. The parameters of the proposed model are identified by a modified particle swarm optimization algorithm. Finally, experiments are conducted on a piezo-actuated nanopositioning stage to validate the proposed P-I model under the sinusoidal inputs. The experimental results show that the developed rate-dependent P-I model precisely characterize the rate-dependent hysteresis loops up to 1000 Hz. [ABSTRACT FROM AUTHOR]

This paper presents a semi-analytical wavelet-based approach for stability analysis of time-periodic delay-differential equations (DDEs) with a single discrete time delay. By using the autocorrelation functions of compactly supported Daubechies scaling functions, the DDE is discretized to a set of algebraic equations, employing the wavelet collocation method. The state transition matrix over a single period is constructed to determine the stability based on Floquet theory. Stability charts for the one-degree-of-freedom milling model and time-delayed Mathieu equation are obtained, illustrating both the efficiency and accuracy of the proposed approach. [ABSTRACT FROM AUTHOR]

Sustained release cellulose acetate (CA) and ethyl cellulose (EC) polymer blend nanofibers loaded with ketoprofen (KET) were successfully prepared by electrospinning. Successful fiber formation has been investigated by using two different binary solvent systems, i.e., acetic acid + distilled water (2:1 v/v) and acetone + N,N-DMAc + ethanol (2:1:1 v/v). Scanning electron microscopy (SEM) images showed that morphological features gradually change as the ratio of both polymers change. Nanofiber diameter also decreases as the CA content is increased in the polymer blend solution from 77.25 ±27 to 72.39 ±30 nm. Drug release profiles were evaluated by in-vitro drug release experiments. Drug release follows a pseudo-Fickian behavior of diffusion and shows a sustained release mechanism. Nanofibers containing more CA show greater controlled release capacity as compared to EC. X-ray diffraction (XRD) patterns of CA and EC polymer blend nanocomposites show that crystalline ketoprofen has changed into an amorphous state. Fourier transform Infrared (FTIR) analysis indicates hydrogen bonding occurs between the drug and the polymer, accounting for molecular integration of the two components. The thermal stability of the prepared polymer blend was also studied using thermo-gravimetric analysis (TGA). A polymer blend sustained release drug delivery system prepared by electrospinning make it possible to fabricate other novel drug releasing systems. [ABSTRACT FROM AUTHOR]

SOX genes play an important role in a number of developmental processes. SOXs have been demonstrated to have potential roles as either tumor suppressors or promoters in various neoplastic tissues depending on the tumor status and type. The aim of this study was to investigate the functional role of SOXs in human cancers. Gene expression changes of SOXs in human hepatocellular carcinoma (HCC) tissues were detected using real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis and immunohistochemistry and compared with those in non-cancerous hepatic tissues. We found by qRT-PCR analysis and immunohistochemistry that the gene SOX8 was significantly upregulated in HCC. Furthermore, we discovered that SOX8 promoted cancer cell proliferation in vitro and that its expression was correlated with elevated β-catenin levels in HCC, whose function was required for the oncogenic effects of SOX8. [ABSTRACT FROM AUTHOR]