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In this paper, a new type of six-degrees of freedom (DOF) flexible parallel mechanism (FPM) is presented. This type of parallel mechanism possesses several favorable properties: 1) its number of DOFs is independent of the number of serial chains which make up the mechanism; 2) it has no kinematical singularities; 3) it is designed to move on rails, and therefore its workspace is much larger than that of a conventional parallel manipulator; and 4) without changing the number of DOFs and the kinematics of the mechanisms, the number of the serial chains can be reconfigured according to the needs of the tasks. These properties make the mechanism very preferable in practice, especially for such tasks as joining huge ship blocks, in which the manipulated objects vary dramatically both in weights and dimensions. Furthermore, the mechanism can be used as either a fully actuated system or an underactuated system. In the fully actuated case, the mechanism has six DOF motion capabilities and manipulation capabilities. However, in the underactuated case, the mechanism still has six DOF motion capabilities, but it has only five DOF manipulation capabilities. In this paper, both the inverse and forward kinematics are studied and expressed in a closed form. The workspace and singularity analysis of the mechanism are also presented. An example is presented to illustrate how to calculate the kinematics of the mechanism in both fully-actuated and underactuated cases. Finally, an application of such a mechanism to manufacturing industry is introduced. Index Terms--Kinematics, manipulator, parallel mechanism, robot, under-actuated system.

Dissolved organic matter (DOM), the most active type of soil organic matter, plays a key role in soil biogeochemical cycling. Therefore, exploring the source, composition, environmental response, and accumulation mechanism of DOM during vegetation succession has great significance for predicting soil carbon cycling. In this study, DOM was extracted from topsoil and subsoil at plots after 12, 30, 40, 50, 80, and 120 years of primary succession along the Hailuogou Glacier retreat area. The concentrations and spectral characteristics of DOM were analyzed via a combination of elemental analysis, ultraviolet-visible spectroscopy, and three-dimensional fluorescence excitation-emission matrix spectroscopy. The results showed that concentrations of soil dissolved organic carbon and dissolved organic nitrogen of both topsoil and subsoil increased significantly during vegetation succession. Along the chronosequence, the protein-like components and optical indices were significantly enhanced, humic-like components and the optical indices decreased, the aromaticity degree of DOM increased first and then decreased. Soil pH and NH4+-N content explained 62.2% of the total variation of surface soil DOM components, while soil moisture and pH explained 64.3% of that of subsurface soil DOM, indicating that environmental conditions were key factors affecting the concentrations and composition of soil DOM in the Hailuogou Glacier retreat area. [ABSTRACT FROM AUTHOR]

The aroma components of white tea from the new tea strain ‘Baiyun 0492’ (also known as Baiyun Tezaocha) and ‘Fuyun 6’ as a control were analyzed and compared by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) in an effort to identify the characteristic aroma components of ‘Baiyun 0492’ white tea. A total of 928 aroma compounds were detected in six white tea samples (of three different grades for each type), and nonyl acetate, contributing to floral and fruity aromas, might be an aroma compound unique to ‘Baiyun 0492’ tea. The results of relative odor activity value (ROAV) analysis showed that β-ionone, linalyl acetate, linalool, (Z)-decan-2-enal, damascenone, neral and citral were the key aroma components in both white teas. Based on orthogonal partial least squares-discriminant analysis (OPLS-DA), the contents of linalool, methyl benzoate, hotrienol, nonyl acetate, 3,7-dimethy-6-actenoic acid and geranyl formate in ‘Baiyun 0492’ tea were significantly higher than those in ‘Fuyun 6’ tea (variable important in the projection (VIP) >1, P < 0.05). Linalsol and methyl benzoate were important aroma compounds of ‘Baiyun 0492’ white tea, responsible for pekoe-like, fruity and floral aromas. This study is helpful for a comprehensive understanding of the aroma characteristics of ‘Baiyun 0492’ white tea, and provides a scientific basis for the research and development of ‘Baiyun 0492’ white tea products with distinctive personality.

Circular RNA (circRNA) is involved in tumor progression. CircPVT1 is an oncogene that is abnormally expressed and correlated with a variety of tumors. It can regulate tumors' malignant behavior and affect the survival and prognosis of patients. This article reviews research on the regulatory roles of circPVT1 in tumors to provide references for accurate treatment.

Clear cell renal cell carcinoma (ccRCC) is a major pathological type of kidney cancer with a poor prognosis due to a lack of biomarkers for early diagnosis and prognosis prediction of ccRCC. In this study, we investigated the aberrant expression of Acyl-coenzyme A oxidase 1 (ACOX1) in ccRCC and evaluated its potential in diagnosis and prognosis. ACOX1 is the first rate-limiting enzyme in the peroxidation β-oxidation pathway and is involved in the regulation of fatty acid oxidative catabolism. The mRNA and protein levels of ACOX1 were significantly downregulated in ccRCC, and its downregulation was closely associated with the tumor-node-metastasis stage of patients. The ROC curves showed that ACOX1 possesses a high diagnostic value for ccRCC. The OS analysis suggested that lower expression of ACOX1 was closely related to the worse outcome of patients. In addition, gene set enrichment analysis suggested that expression of ACOX1 was positively correlated with CDH1, CDH2, CDKL2, and EPCAM, while negatively correlated with MMP9 and VIM, which strongly indicated that ACOX1 may inhibit the invasion and migration of ccRCC by reversing epithelial-mesenchymal transition. Furthermore, we screened out that miR-16-5p is upregulated at the mRNA transcript level in ccRCC and negatively correlated with ACOX1. In conclusion, our results showed that ACOX1 is abnormally low expressed in ccRCC, suggesting that it could serve as a diagnostic and prognostic biomarker for ccRCC. Overexpression of miR-16-5p may be responsible for the inactivation of ACOX1.