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The 6RUS parallel manipulator is a highly versatile and widely used robotic mechanism with six degrees of freedom. Its intricate kinematic structure and its capability to perform complex motion tasks have garnered significant research interest in recent years. The kinematic analysis of the 6RUS mechanism plays a crucial role in understanding its operational characteristics and optimizing its performance for various applications. In this paper, we present a state-of-the-art kinematic algorithm for the 6RUS parallel manipulator. Our algorithm is aimed at addressing the challenges associated with accurately determining the pose and motion of the end-effector relative to the base, considering the complexity of the mechanism's architecture. By leveraging advanced mathematical modeling techniques and utilizing efficient computational algorithms, our proposed algorithm offers improved accuracy, efficiency, and robustness in determining the kinematic parameters of the 6RUS mechanism. The key contributions of this work include the development of a comprehensive forward and inverse kinematic model for the 6RUS parallel manipulator, incorporating the effects of joint constraints, singularities, and workspace limitations. We also present a detailed analysis of the algorithm's performance in comparison to existing approaches, demonstrating its superiority in terms of computational efficiency and accuracy. The proposed kinematic algorithm holds significant potential for enhancing the design, control, and trajectory planning of 6RUS parallel manipulators. It provides a solid foundation for advanced applications such as robotic surgery, industrial automation, and virtual reality systems. The results presented in this paper contribute to the growing body of knowledge in parallel manipulator research and pave the way for future developments in the field. [ABSTRACT FROM AUTHOR]

Passive heat dissipation cooling technologies based on natural convection in open channels can effectively control the maximum temperature and improve the temperature homogeneity of 5G base stations, data centers and other equipment. In this paper, the flow and heat transfer of natural convection in an open-ended square channel with two suspending heat sources are studied through numerical simulation. The distributions of the temperature field and flow field in the channel with different horizontal distances and vertical altitude differenced of the heat sources are acquired via the finite element method (FEM)-based COMSOL Multiphysics. The changes in local temperature and the local Nusselt number are obtained. The relationships between the temperature field, flow field, and Nusselt number with respect to the geometric parameters of the heat sources are discussed. With different geometric parameters of the two suspending heat sources, the average surface temperature at the bottom is always lower than the top, while the average Nusselt number reaches maximum and minimum values at the bottom and top surfaces, respectively. As the horizontal distance increases, the maximum vertical airflow velocity decreases. The average surface temperature and local Nusselt number go through a V-shape and reverse V-shape tendency, respectively. The maximum temperature at the surface of the heat source is 397 K at a horizontal distance of 0.36 m. The local Nusselt number on the side of the heat source reaches its maximum at a horizontal distance of 0.28 m with an average value of 33.5. As the vertical altitude difference increases, the temperature difference between the heat sources increases from 0 K to 54 K, and the maximum vertical airflow velocity goes through a reverse V-shape tendency. The Nusselt number of the right heat source decreases to a certain value of about 20, while that of the left heat source goes through a fluctuating tendency. The results show that the best arrangement of the heat sources is a vertical altitude difference of 0 m and a horizontal distance of 0.28 m. [ABSTRACT FROM AUTHOR]

A highly enantioselective cyclopropanation to synthesize pyrimidine-substituted diester D–A cyclopropanes is reported. Various N1-vinylpyrimidines react well with phenyliodonium ylides, delivering chiral cyclopropanes in up to 97% yield with up to 99% ee. Through simple [3+2] annulation with benzaldehyde or ethyl glyoxylate, different chiral pyrimidine nucleoside analogues with a sugar ring could be obtained. [ABSTRACT FROM AUTHOR]

Fibulin-1 (FBLN1) is involved in the progression of some types of cancer. However, the role of FBLN1 in cutaneous melanoma (CM) has not been examined. The purpose of this study was to understand the molecular mechanisms and clinical significance of FBLN1 inactivation in CM. The expression of FBLN1 mRNA in CM tissues and adjacent normal skin tissues was analyzed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Methylation-specific polymerase chain reaction was performed to examine the methylation status of the FBLN1 gene promoter. Furthermore, the methylation status of FBLN1 was analyzed with the clinicopathological characteristics and overall survival. qRT-PCR showed FBLN1 mRNA levels in cancerous tissues to be significantly decreased compared with that in adjacent normal skin tissues. The rate of FBLN1 promoter methylation was significantly higher in CM tissues than in adjacent normal skin tissues ( P < 0.001). Downregulation of FBLN1 was strongly correlated with promoter methylation ( P = 0.021). Promoter hypermethylation of FBLN1 was significantly associated with tumor stage ( P = 0.019). In addition, FBLN1 methylation status was associated with significantly shorter survival time and was an independent predictor of overall survival. In conclusion, our results indicated that FBLN1 is a novel candidate of tumor suppressor gene and that promoter hypermethylation of FBLN1 is associated with tumor progression in CM. [ABSTRACT FROM AUTHOR]

Thymidine kinase 1 (TK1) is involved in cancer progression. Metastatic site is a prognostic factor in melanoma. We assessed whether serum levels of TK1 are associated with metastatic sites or prognosis in patients treated for stage IV melanoma. The study included 64 patients, who received dacarbazine or four-drug chemotherapy (dacarbazine, vincristine, bleomycin, and lomustine) both combined with interferon-alfa. Serum samples for TK1 were analyzed by ELISA. The patients ( n = 22) with only skin and subcutaneous metastases had significantly lower mean TK1 levels (1,639 pg/ml) than the patients ( n = 42) with other distant metastases (2,586 pg/ml, Mann-Whitney, p = 0.031). TK1 levels above the median (1,590 pg/ml) were significantly related to deep lymph node involvement (odds ratios 3.672; 95 % confidence intervals 1.024-12.843, p = 0.036). There were no other significant associations between TK1 levels and tumor burden nor were the levels significantly related to the response to therapy or survival. Those eight patients who had received previous adjuvant IFN-alfa therapy had lower mean TK1 levels (1,735 pg/ml) as compared to those 56 patients without previous IFN-alfa therapy (2,338 pg/ml, analysis of variance, p = 0.026). This is the first study exploring serum TK1 in melanoma. TK1 might be involved in the deep lymphatic dissemination and progression of melanoma metastasis. [ABSTRACT FROM AUTHOR]

Recently, it was reported that soluble MICB (sMICB) may impair tumor immunogenicity by reducing natural killer group 2D ligand densities on malignant cells. The aim of this study was to elucidate the role of sMICB in melanoma patients. In the present study, we determined sMICB serum concentration in 125 melanoma patients of different clinical stages of disease compared with 30 healthy controls using an ELISA. The correlations between sMICB serum concentration and clinicopathologic variables were analyzed. sMICB serum level was significantly elevated ( P < 0.0005) in melanoma patients (mean ± SE = 8.60 ± 0.26 ng/ml) compared with healthy controls (mean ± SE = 6.27 ± 0.25 ng/ml). Univariate analysis revealed a correlation of sMICB serum concentration with advanced stages of disease ( P = 0.009). Only a slight increase in sMICB serum level ( P = 0.057) could be observed in regard to the tumor burden. Patients undergoing current treatment with cytostatics ( n = 18) revealed a strong increase in sMICB serum level ( P < 0.0005), whereas treatment with IFN-α alone or combined with cytostatics ( n = 19) showed no change in serum sMICB concentration. According to Kaplan-Meier analysis, elevated sMICB serum levels were associated with a poor overall and a progression-free survival. Multivariate analysis revealed sMICB serum concentration as an independent predictive factor for progression-free and overall survival. Our results show a prognostic relevance of serum sMICB in melanoma patients, indicating that the evaluation of sMICB serum level may be important for the selection of therapeutic strategies. [ABSTRACT FROM AUTHOR]