Material Removal Mechanism of SiC Ceramic by Porous Diamond Grinding Wheel Using Discrete Element Simulation.

SiC ceramics are typically hard and brittle materials. Serious surface/subsurface damage occurs during the grinding process due to the poor self-sharpening ability of monocrystalline diamond grits. Nevertheless, recent findings have demonstrated that porous diamond grits can achieve high-efficiency and low-damage machining. However, research on the removal mechanism of porous diamond grit while grinding SiC ceramic materials is still in the bottleneck stage. A discrete element simulation model of the porous diamond grit while grinding SiC ceramics was established to optimize the grinding parameters (e.g., grinding wheel speed, undeformed chip thickness) and pore parameters (e.g., cutting edge density) of the porous diamond grit. The influence of these above parameters on the removal and damage of SiC ceramics was explored from a microscopic perspective, comparing with monocrystalline diamond grit. The results show that porous diamond grits cause less damage to SiC ceramics and have better grinding performance than monocrystalline diamond grits. In addition, the optimal cutting edge density and undeformed chip thickness should be controlled at 1-3 and 1-2 um, respectively, and the grinding wheel speed should be greater than 80 m/s. The research results lay a scientific foundation for the efficient and low-damage grinding of hard and brittle materials represented by SiC ceramics, exhibiting theoretical significance and practical value.

Interleukin-6 Concentration in Single-Embryo Medium Is Associated with Blastocyst Formation.

IL-6 plays an important role in oogenesis in humans. However, at the preimplantation stage, IL-6 production and the role in embryo development remain unclear. In this study, IL-6 concentrations in single-embryo media were analyzed. In addition, the association between IL-6 production and blastocyst formation was investigated. Single-embryo culture media from 194 embryos were collected on day 6 after fertilization and divided into four groups according to the developmental stage of the corresponding embryo, as follows: cleavage stage group, morula-early blastocyst group, unavailable full blastocyst group, and available full blastocyst group. IL-6 concentrations were significantly lower in the cleavage stage group than in the morula-early blastocyst group (p = 0.009), in the unavailable full blastocyst group (p = 0.003), and in the available full blastocyst group (p < 0.001). Logistic regression analysis showed that IL-6 concentration in single-embryo medium was significantly associated with blastocyst formation (odds ratios ß1 = 1.876, 95% CI 1.433 to 2.644, p < 0.0001). Therefore, IL-6 was produced by human preimplantation embryos throughout the preimplantation stage and may play a role in embryo development.

Deciphering the roles of myeloid derived suppressor cells in viral oncogenesis.

Myeloid derived suppressor cells (MDSCs) are a heterogenous population of myeloid cells derived from monocyte and granulocyte precursors. They are pathologically expanded in conditions of ongoing inflammation where they function to suppress both innate and adaptive immunity. They are subdivided into three distinct subsets: monocytic (M-) MDSC, polymorphonuclear (or neutrophilic) (PMN-) MDSC and early-stage (e-) MDSC that may exhibit differential function in different pathological scenarios. However, in cancer they are associated with inhibition of the anti-tumour immune response and are universally associated with a poor prognosis. Seven human viruses classified as Group I carcinogenic agents are jointly responsible for nearly one fifth of all human cancers. These viruses represent a large diversity of species, including DNA, RNA and retroviridae. They include the human gammaherpesviruses (Epstein Barr virus (EBV) and Kaposi's Sarcoma-Associated Herpesvirus (KSHV), members of the high-risk human papillomaviruses (HPVs), hepatitis B and C (HBV, HCV), Human T cell leukaemia virus (HTLV-1) and Merkel cell polyomavirus (MCPyV). Each of these viruses encode an array of different oncogenes that perturb numerous cellular pathways that ultimately, over time, lead to cancer. A prerequisite for oncogenesis is therefore establishment of chronic infection whereby the virus persists in the host cells without being eradicated by the antiviral immune response. Although some of the viruses can directly modulate the immune response to enable persistence, a growing body of evidence suggests the immune microenvironment is modulated by expansions of MDSCs, driven by viral persistence and oncogenesis. It is likely these MDSCs play a role in loss of immune recognition and function and it is therefore essential to understand their phenotype and function, particularly given the increasing importance of immunotherapy in the modern arsenal of anti-cancer therapies. This review will discuss the role of MDSCs in viral oncogenesis. In particular we will focus upon the mechanisms thought to drive the MDSC expansions, the subsets expanded and their impact upon the immune microenvironment. Importantly we will explore how MDSCs may modulate current immunotherapies and their impact upon the success of future immune-based therapies.

Prognostic value of MAGE-A9 expression in patients with colorectal cancer.

MAGE-A9 is a novel member of the melanoma-associated antigen (MAGE) family and is expressed in testicular cancer. The present study investigated MAGE-A9 expression as a potential biomarker in colorectal cancer (CRC). Immunohistochemical analysis was used to determine the expression of MAGE-A9 in 201 cases CRC tissues. We used quantitative real-time polymerase chain reaction (RT-PCR) and western blot analysis to further verify the results. The correlation between MAGE-A9 expression, clinicopathological features and prognosis of CRC patients was analyzed. The results showed that MAGE-A9 was predominantly localized in the cytoplasm of cancer cells and stromal cells. Compared to normal adjacent tissues, the high expression rate of MAGE-A9 in CRC tissues was significantly increased (P<0.001). High MAGE-A9 expression was significantly associated with venous invasion (P=0.008) and lymph node metastasis (P<0.001). The survival rate of the CRC patients who were positive for MAGE-A9 expression was significantly lower than that of CRC patients with negative MAGE-A9 expression. Moreover, univariate and multivariate analyses showed that high MAGE-A9 expression was a poor prognostic factor for CRC patients. Hence, MAGE-A9 is expected to become a new target for CRC treatment.

Stability and conformational change of methoxypolyethylene glycol modification for native and unfolded trypsin.

The effect of succinimidyl carbonates activated methoxypolyethylene glycol (mPEG-SC) on the catalytic properties and conformation of native trypsin and dynamic high-pressure microfluidisation (DHPM) induced unfolded trypsin was studied. The thermal stability of unfolded trypsin was enhanced more significantly than that of native trypsin between 45 and 70°C. The autolysis analysis indicated that modified unfolded trypsin was markedly more resistant to autolysis compared to modified native trypsin between 40 and 180min. Upon mPEG-SC conjugation, the Km value of the enzyme decreased by about 2-fold, and the catalytic efficiency (Kcat/Km) increased by about 3-4-fold. Moreover, the increased thermal stability of unfolded trypsin might be due to the lower surface hydrophobicity and the higher hydrogen bond formation after mPEG-SC modification, which was reflected in the decrease of UV absorbance, the quenching and blue shift of fluorescence spectra, as well as the increase of ß-sheet content.

The effect of citric acid on the activity, thermodynamics and conformation of mushroom polyphenoloxidase.

Few reports have focused on the effect of citric acid on thermodynamics and conformation of polyphenoloxidase (PPO). In this study, variations on activity, thermodynamics and conformation of mushroom PPO induced by citric acid (1-60mM) and relationships among these were investigated. It showed that with the increasing concentration of citric acid, the activity of PPO decreased gradually to an inactivity condition; inactivation rate constant (k) of PPO increased and the activation energy (Ea) as well as thermodynamic parameters (ΔG, ΔH, ΔS) decreased, which indicated that the thermosensitivity, stability and number of non-covalent bonds of PPO decreased. The conformation was gradually unfolded, which was reflected in the decrease of α-helix contents, increase of ß-sheet and exposure of aromatic amino acid residuals. Moreover, two linear relationships of relative activities, enthalpies (ΔH) against α-helix contents were obtained. It indicated that changes of activity and thermodynamics might correlate to the unfolding of conformation.

[Protective effect of Uncaria rhynchophylla total alkaloids pretreatment on hippocampal neurons after acute hypoxia].

OBJECTIVE: To investigate the effect of Uncaria rhynchophylla total alkaloids (RTA) pretreatment on the voltage-gated sodium currents of the rat hippocampal neurons after acute hypoxia. METHOD: Primary cultured hippocampal neurons were divided into RTA pre-treated and non-pretreated groups. Patch clamp whole-cell recording was used to compare the voltage-gated sodium current amplitude and threshold with those before hypoxia. RESULT: After acute hypoxia, sodium current amplitude was significantly decreased and its threshold was upside. RTA pretreatment could inhibit the reduction of sodium current amplitude. CONCLUSION: RTA pretreatment alleviates the acute hypoxia-induced change of sodium currents, which may be one of the mechanisms for protective effect of RTA on cells.