Search Results (31)

Background/Objectives: Papillary thyroid microcarcinoma (MPTC), a subset of papillary thyroid carcinoma (PTC), is increasingly detected with advanced imaging. While most MPTCs are indolent, some exhibit aggressive behavior, complicating clinical management. The BRAF V600E mutation, common in PTC, is linked to aggressive features, and its allele frequency (AF) may serve as a biomarker for tumor aggressiveness. This study explored the association between BRAF V600E AF and aggressive histopathological features in MPTC. Methods: Data from 1 January 2016 to 23 December 2023 were retrieved from two McGill University teaching hospitals. Inclusion criteria comprised patients aged ≥ 18 years with thyroid nodules ≤ 1 cm, documented BRAF V600E mutation and AF results, and available surgical pathology reports. Tumor aggressiveness was defined as the presence of lymph node metastasis, aggressive histological subtype (tall cell, hobnail, columnar, solid/trabecular or diffuse sclerosing), extra thyroidal extension, or extensive lymphovascular extension. Associations were explored using t-tests. Results: Among 1564 records, 34 met the inclusion criteria and were included in analyses. The mean BRAF V600E AF was significantly higher in aggressive tumors (23.58) compared to non-aggressive tumors (13.73) (95% CI: −18.53 to −1.16, p = 0.03). Although not statistically significant, trends were observed for higher BRAF V600E AF in tumors with lymph node metastasis (mean AF: 25.4) compared to those without (mean AF: 16.67, p = 0.08). No significant difference was noted in BRAF V600E AF by histological subtype (mean AF for aggressive: 19.57; non-aggressive: 19.15, p = 0.94). Conclusions: Elevated BRAF V600E AF is associated with aggressive behavior in MPTC, highlighting its potential as a biomarker to inform treatment strategies. Larger studies are warranted to validate these findings and enhance clinical management of MPTC patients. Full article

The dual three-phase permanent magnet synchronous motor (DT-PMSM) has the advantages of high fault tolerance, flexible control, small torque ripple, and meeting the requirements of low voltage and high power. However, in the traditional model of predictive torque control (MPTC) of DT-PMSM, the calculation is cumbersome due to the numerous voltage vectors. Therefore, a fast-switching table based on torque prediction DT-PMSM control is established. In addition, in the DT-PMSM conventional MPTC strategy, the cost function consists of the electromagnetic torque error and the stator flux error. Due to the lack of an explicit theory to guide the design of the weight coefficients, the weight coefficients can only be set through a large number of simulations and experiments in applications, and the tuning process is very cumbersome. Therefore, the support vector machine regression (SVR) method was used to improve the tedious calculation and tuning process of MPTC of DT-PMSM. The experimental results show that MPTC based on a fast-switching table achieves good steady-state and dynamic control performance by using weighting factors. Full article

Owing to their high performance and high-efficiency controllability, surface-mounted permanent magnet synchronous motors (SPMSMs) have been widely considered for various robotic systems. The conventional three-vector-based model predictive torque control (MPTC) is frequently applied to SPMSMs, while the adjustment of weight factors is difficult. Compared with the five-segment sequence output method, the three-segment sequence output method can effectively reduce the switching frequency. However, the three-segment sequence output method leads to large torque and stator flux ripple. For these issues, a three-vector-based smart MPTC method based on the optimal vector sequence optimized by a genetic algorithm is proposed. Firstly, the reference voltage vector output from the discrete-time sliding mode (DTSM) current controller is utilized to simplify the process of selecting the vectors, and it can enhance the robustness of the SPMSM system. Secondly, an improved cost function is employed to select the optimal vector sequence, aiming to minimize torque and flux ripple. Furthermore, the multi-objective genetic algorithm is leveraged to seek the Pareto solution for weight factors. As a final step, the efficacy of the designed MPTC approach is confirmed through simulations and experiments. Full article

The model predictive-torque-control strategy of a permanent magnet synchronous motor (PMSM) has many advantages such as a fast dynamic response and the ease of implementation. However, when the permanent magnet motor has a large number of pole pairs or operates at high-speed, due to constraints such as the inverter switching frequency, sampling time, and algorithm execution time, the motor carrier ratio (the ratio of control frequency to operating frequency) becomes relatively low. The discrete model derived from and based on the forward Euler method has a large model error when the carrier ratio decreases, which leads to voltage vector misjudgment and inaccurate duty cycle calculation, thus leading to the decline of control performance. Meanwhile, the shortcomings of the traditional model predictive-torque-control strategy limit the steady-state performance. In response to the above issues, this paper proposes an improved model predictive-torque-control strategy suitable for low-carrier-ratio conditions. The strategy consists of an improved discrete model that considers rotor-angle-position variations and a model prediction algorithm. It also analyzes the sensitivity of model predictive control to parameter changes and designs an online parameter optimization algorithm. Compared with the traditional forward Euler method, the improved discrete model proposed in this paper has obvious advantages under low-carrier-ratio conditions; at the same time, the parameter optimization process enhances the parameter robustness of the model prediction algorithm. Moreover, the proposed model predictive-torque-control strategy has high torque tracking accuracy. The experimental results verify the feasibility and effectiveness of the proposed strategy. Full article

This study explores the development of core–shell electrocatalysts for efficient glycerol oxidation in alkaline media. Carbon-supported M@Pt/C (M = Co, Ni, Sn) catalysts with a 1:1 atomic ratio of metal (M) to platinum (Pt) were synthesized using a facile sodium borohydride reduction method. The analysis confirmed the formation of the desired core–shell structure, with Pt dominating the surface as evidenced by energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) revealed the presence of a face-centered cubic (fcc) Pt structure for Co@Pt/C and Ni@Pt/C. Interestingly, Sn@Pt/C displayed a PtSn alloy formation indicated by shifted Pt peaks and the presence of minor Sn oxide peaks. Notably, no diffraction peaks were observed for the core metals, suggesting their amorphous nature. Electrocatalytic evaluation through cyclic voltammetry (CV) revealed superior glycerol oxidation activity for Co@Pt/C compared to all other catalysts. The maximum current density followed the order Co@Pt/C > Ni@Pt/C > Sn@Pt/C > Pt/C. This highlights the effectiveness of the core–shell design in enhancing activity. Furthermore, Sn@Pt/C displayed remarkable poisoning tolerance attributed to a combined effect: a bifunctional mechanism driven by Sn oxides and an electronic effect within the PtSn alloy. These findings demonstrate the significant potential of core–shell M@Pt/C structures for designing highly active and poisoning-resistant electrocatalysts for glycerol oxidation. The presented approach paves the way for further development of optimized catalysts with enhanced performance and stability aiming at future applications in direct glycerol fuel cells. Full article

To overcome the drawbacks of large torque ripples and high harmonic contents in a dual three-phase permanent magnet synchronous motor (PMSM) used in electric vehicle drive systems, a double-virtual-vector-based model predictive torque control (DVV-MPTC) strategy was proposed in this paper. Firstly, 12 virtual voltage vectors were constructed to minimize harmonic interference as much as possible. Then, the DVV-MPTC strategy is proposed to solve the problem of large torque ripples caused by single-virtual-vector-based MPTC (SVV-MPTC) method. On the other hand, an enhancement to the cost function was also introduced to resolve the challenges of tuning weight coefficients. Experimental comparisons between traditional direct torque control (DTC), SVV-MPTC method, and the proposed DVV-MPTC strategy were carried out, which show that the latter achieves significant improvements. In particular, it can reduce both harmonic components and torque ripple compared to traditional control strategies, resulting in a more efficient and stable performance for the electric drive system. Full article

Traditional model predictive torque control (MPTC) predicts the torque and flux values for the next time step and selects the voltage vector that minimizes the cost function as the optimal vector to apply to the inverter. This control approach is straightforward and allows for multi-objective control, but it has some issues in terms of the dynamic steady-state performance and parameter robustness. Therefore, this paper proposes a weightless model predictive control method based on an extended state observer (ESO). By designing an improved ESO to observe and compensate for motor parameter disturbances in real time, and employing a novel 2-D switching table and voltage vector sector selection diagram, the method evaluates three out of eight voltage vectors based on the torque and stator flux error signals. This reduces the computational load while increasing the number of candidate voltage vectors. Finally, a cost function without weighting factors is designed to lower the computational complexity. The simulation results show that the proposed new control method effectively reduces the torque and flux ripple and improves the current waveform compared to traditional MPTC. Full article

Background: Papillary thyroid carcinoma (PTC) is the most common type of differentiated TC, while medullary TC (MTC) accounts for 4%. The concomitant presence of PTC and MTC is rare. Methods: This is a retrospective, single-center observational study conducted over 16 years (2001–2017). The data were collected from the clinical records of patients who underwent total thyroidectomy at the Endocrine Unit-Department of Medicine of the University Hospital of Pisa, Italy. Results: Over 690 analyzed cases, 650 (94.2%) were exclusive DTC, 19 exclusive MTC (2.75%) and 5 PTC/MTC (0.7%). No case of mixed medullary/follicular TC or hereditary MTC (familial MTC/multiple endocrine neoplasia type 2) was found. Among the five PTC/MTC cases, there was a male prevalence (M:F = 3:2), and all PTC components were at stage I, whereas 40% of MTC were at stage I and III and 20% of MTC were at stage II; microPTC (mPTC) was prevalent (80%) and also microMTCs were frequent (40%); 60% of MTC patients recovered, while 40% of patients developed metastatic disease. The search for germline mutations of the RET gene resulted in being negative in all cases. Conclusions: The incidence of PTC/MTC has been increasing over the past 30 years. The etiology of PTC/MTC forms is still unknown, and although this simultaneous occurrence could be only a coincidence, we cannot exclude the hypothesis of a shared genetic origin. Full article

The permanent-magnet synchronous motor (PMSM), with the advantages of low energy consumption and stable operation, is considered a green power source to replace gasoline engines. Motor control is the core problem of the electric-drive system, so it is important to study the high-performance motor control algorithm. The traditional PMSM control strategy has problems such as torque pulsation, large overshoot, and parameters which are not easy to adjust. This work proposes a new model-predictive torque control (MPTC) based on multi-objective ranking for these issues. The Romberg observer was utilized to accurately estimate motor flux and torque across a wide range of speeds and ensure optimal performance of the MPTC. The optional voltage vectors were classified using graph theory. The model’s cost function was optimized and the control delay caused by hardware processing was compensated by a modified Euler method. A multi-objective ranking method was used to avoid the offline selection of MPTC weight coefficients. Additionally, one ranking method was used to reduce the complexity of the algorithm for multiple objectives. Based on the simulation results, the newly proposed MPTC method, when compared with traditional approaches, reduced the total harmonic distortion from 2.78% to 2.26%. Torque ripple decreased by approximately 58.4%, and the switching frequency was reduced by 3.05%, lowering the inverter’s switching losses. Therefore, the newly proposed MPTC had faster torque response, reduced computation time, and less torque pulsation, which further improved the dynamic performance of the permanent-magnet synchronous motor. Full article

Thirty to 50% of differentiated thyroid carcinomas include papillary thyroid microcarcinomas (mPTC). Most of these tumors remain clinically silent, have a bright prognosis and a disease-specific mortality <1%. Surgery has been recommended as first line-treatment by current guidelines, the standard treatment being lobectomy. However, surgery has some drawbacks, including potential recurrent laryngeal nerve paralysis, hypothyroidism, hypoparathyroidism, in -patient basis hospital stay, lifelong medication, scarring of the neck, and general anesthesia related risks. Moreover, elderly patients who present severe comorbidities, could be ineligible for surgery, and others may refuse invasive surgery. Another option supported by the American Thyroid Association is active surveillance. This option can be considered as unattractive and difficult to accept by European patients, as there is a 2–6% risk of disease progression. Percutaneous image-guided thermal ablation has been successfully applied in the treatment of liver and lung tumors in the 1990s and 2000s; and has recently been proposed as an alternative to surgery in patients presenting with thyroid diseases. This minimally invasive treatment has similar efficacy, fewer complications, better quality of life and cosmetic outcomes than surgery. We report herein two cases of radiofrequency ablation of mPTC and T2 PTC in elderly patients who were ineligible for surgery. Full article

This paper presents a model predictive thrust force control (MPTFC) method for a multiple-modular permanent magnet synchronous linear motor (PMSLM). It focuses on the thrust assignment and thrust ripple of the motor drive system with a multiple-branch inverter. A discrete time model of the PMSLM is established, and the driving system structure and operation principle of the motor are studied. A multi-mode cost function is designed according to the requirements of the different load conditions, and the optimal voltage vector action time is determined. The operation mode is analyzed to determine the distribution factor, so as to reduce the thrust pulsation during operation and improve the performance of the drive system. The results indicate that the proposed MPTFC method is effective in different operating modes, and the drive system has high efficiency and safer performance compared to a conventional drive system. Full article

The current prevailing paradigm in the renin-angiotensin system dictates that most, if not all, biological, physiological, and pathological responses to its most potent peptide, angiotensin II (Ang II), are mediated by extracellular Ang II activating its cell surface receptors. Whether intracellular (or intracrine) Ang II and its receptors are involved remains incompletely understood. The present study tested the hypothesis that extracellular Ang II is taken up by the proximal tubules of the kidney by an AT₁ (AT_1a) receptor-dependent mechanism and that overexpression of an intracellular Ang II fusion protein (ECFP/Ang II) in mouse proximal tubule cells (mPTC) stimulates the expression of Na⁺/H⁺ exchanger 3 (NHE3), Na⁺/HCO₃^- cotransporter, and sodium and glucose cotransporter 2 (Sglt2) by AT_1a/MAPK/ERK1/2/NF-kB signaling pathways. mPCT cells derived from male wild-type and type 1a Ang II receptor-deficient mice (Agtr1a^-/-) were transfected with an intracellular enhanced cyan fluorescent protein-tagged Ang II fusion protein, ECFP/Ang II, and treated without or with AT₁ receptor blocker losartan, AT₂ receptor blocker PD123319, MEK1/MEK2 inhibitor U0126, NF-кB inhibitor RO 106-9920, or p38 MAP kinase inhibitor SB202196, respectively. In wild-type mPCT cells, the expression of ECFP/Ang II significantly increased NHE3, Na⁺/HCO₃^-, and Sglt2 expression (p < 0.01). These responses were accompanied by >3-fold increases in the expression of phospho-ERK1/2 and the p65 subunit of NF-кB (p < 0.01). Losartan, U0126, or RO 106-9920 all significantly attenuated ECFP/Ang II-induced NHE3 and Na⁺/HCO₃^- expression (p < 0.01). Deletion of AT₁ (AT_1a) receptors in mPCT cells attenuated ECFP/Ang II-induced NHE3 and Na⁺/HCO₃^- expression (p < 0.01). Interestingly, the AT₂ receptor blocker PD123319 also attenuated ECFP/Ang II-induced NHE3 and Na⁺/HCO₃^- expression (p < 0.01). These results suggest that, similar to extracellular Ang II, intracellular Ang II may also play an important role in Ang II receptor-mediated proximal tubule NHE3, Na⁺/HCO₃^-, and Sglt2 expression by activation of AT_1a/MAPK/ERK1/2/NF-kB signaling pathways. Full article

The induction motor (IM) drives are prone to various uncertainties, disturbances, and non-linear dynamics. A high-performance control system is essential in the outer loop to guarantee the accurate convergence of speed and torque to the required value. Super-twisting sliding mode control (ST-SMC) and fractional-order calculus have been widely used to enhance the sliding mode control (SMC) performance for IM drives. This paper combines the ST-SMC and fractional-order calculus attributes to propose a novel super-twisting fractional-order sliding mode control (ST-FOSMC) for the outer loop speed control of the model predictive torque control (MPTC)-based IM drive system. The MPTC of the IM drive requires some additional sensors for speed control. This paper also presents a novel machine learning-based Gaussian Process Regression (GPR) framework to estimate the speed of IM. The GPR model is trained using the voltage and current dataset obtained from the simulation of a three-phase MPTC based IM drive system. The performance of the GPR-based ST-FOSMC MPTC drive system is evaluated using various test cases, namely (a) electric fault incorporation, (b) parameter perturbation, and (c) load torque variations in Matlab/Simulink environment. The stability of ST-FOSMC is validated using a fractional-order Lyapunov function. The proposed control and estimation strategy provides effective and improved performance with minimal error compared to the conventional proportional integral (PI) and SMC strategies. Full article

Isoniazid (INH) is an antibiotic that is widely used to treat tuberculosis (TB). Adaptation to environmental stress is a survival strategy for Mycobacterium tuberculosis and is associated with antibiotic resistance development. Here, mycobacterial adaptation following INH treatment was studied using a multi-stress system (MS), which mimics host-derived stress. Mtb H37Rv (drug-susceptible), mono-isoniazid resistant (INH-R), mono-rifampicin resistant (RIF-R), and multidrug-resistant (MDR) strains were cultivated in the MS with or without INH. The expression of stress-response genes (hspX, tgs1, icl1, and sigE) and lipoarabinomannan (LAM)-related genes (pimB, mptA, mptC, dprE1, dprE2, and embC), which play important roles in the host–pathogen interaction, were measured using real-time PCR. The different adaptations of the drug-resistant (DR) and drug-susceptible (DS) strains were presented in this work. icl1 and dprE1 were up-regulated in the DR strains in the MS, implying their roles as markers of virulence and potential drug targets. In the presence of INH, hspX, tgs1, and sigE were up-regulated in the INH-R and RIF-R strains, while icl1 and LAM-related genes were up-regulated in the H37Rv strain. This study demonstrates the complexity of mycobacterial adaptation through stress response regulation and LAM expression in response to INH under the MS, which could potentially be applied for TB treatment and monitoring in the future. Full article

Two Zn(II) coordination polymers (CPs) based on n-methylpyridyltriazole carboxylate semi-rigid organic ligands (n-MPTC), with n = 3 (L1) and 4 (L2), have been prepared at the water n-butanol interphase by reacting Zn(NO₃)₂·4H₂O with NaL1 and NaL2. This allows us to systematically investigate the influence of the isomeric positional effect on their structures. The organic ligands were obtained by saponification from their respective ester precursors ethyl-5-methyl-1-(pyridin-3-ylmethyl)-1H-1,2,3-triazole-4-carboxylate (P1) and ethyl-5-methyl-1-(pyridin-4-ylmethyl)-1H-1,2,3-triazole-4-carboxylate (P2), resulting in their corresponding sodium salt forms, 3-MPTC, and 4-MPTC. The structure of the Zn(II) CPs determined by single-crystal X-ray diffraction reveals that both CPs have 2D supramolecular hydrogen bond networks. The 2D supramolecular network of [Zn(L1)]n (1) is built up by hydrogen bond interactions between oxygen and hydrogen atoms between neighboring n-methylpyridyltriazole molecules, whereas in [Zn(L2)·4H₂O]n (2) the water molecules link 1D polymeric chains forming a 2D supramolecular aggregate. The structures of 1 and 2 clearly show that the isomeric effect in the semi-rigid ligands plays a vital role in constructing the Zn(II) coordination polymers, helped by the presence of the methylene spacer group, in the final structural conformation. The structures of 1 and 2 significantly affect their luminescent properties. Thus, while 2 shows strong emission at room temperature centered at 367 nm, the emission of 1 is quenched substantially. Full article