Effect of frequency coupling on stability analysis of a grid-connected modular multilevel converter system

Due to the internal dynamics of the modular multilevel converter (MMC), the coupling between the positive and negative sequences in impedance, which is defined as frequency coupling, inherently exists in MMC. Ignoring the frequency coupling of the MMC impedance model may lead to inaccurate stability assessment, and thus the multi-input multi-output (MIMO) impedance model has been developed to consider the frequency coupling effect. However, the generalized Nyquist criterion (GNC), which is used for the stability analysis of an MIMO model, is more complicated than the stability analysis method applied on single-input-single-output (SISO) models. Meanwhile, it is not always the case that the SISO model fails in the stability assessment. Therefore, the conditions when the MIMO impedance model needs to be considered in the stability analysis of an MMC system should be analyzed. This paper quantitatively analyzes the effect of frequency coupling on the stability analysis of grid-connected MMC, and clarifies the frequency range and grid conditions that the coupling effect required to be considered in the stability analysis. Based on the quantitative relations between the frequency coupling and the stability analysis of the grid-connected MMC system, a simple and accurate stability analysis method for the grid-connected MMC system is proposed, where the MIMO impedance model is applied when the frequency coupling has a significant effect and the SISO impedance model is used if the frequency coupling is insignificant

Neutron Activation Background in the NvDEx Experiment

An extremely low-background environment is a crucial requirement for any neutrinoless double beta decay experiment. Neutrons are very difficult to stop, because they can pass through the shields and activate nuclei in the detector, even inside the fiducial volume itself. Using Geant4 simulations we have studied the neutron background for N$\nu$DEx-100 and the most efficient way to reduce it. Using a 60 cm thick external HDPE shield the neutron background can be reduced down to $0.24\pm 0.06$ events/year, lower than the background rate due to natural radioactivity (0.42 events/year), which was used as a benchmark for these calculations. The amount of shielding material needed can be significantly reduced by placing HDPE in the empty space between the lead shield and the steel vessel; in this way, it is sufficient to add 20 cm external HDPE shield to reduce the neutron background down to $0.15\pm0.05$ events/year.Comment: 13 pages, 11 figure

VEGF Is Involved in the Increase of Dermal Microvascular Permeability Induced by Tryptase

Tryptases are predominantly mast cell-specific serine proteases with pleiotropic biological activities and play a critical role in skin allergic reactions, which are manifested with rapid edema and increases of vascular permeability. The exact mechanisms of mast cell tryptase promoting vascular permeability, however, are unclear and, therefore, we investigated the effect and mechanism of tryptase or human mast cells (HMC-1) supernatant on the permeability of human dermal microvascular endothelial cells (HDMECs). Both tryptase and HMC-1 supernatant increased permeability of HDMECs significantly, which was resisted by tryptase inhibitor APC366 and partially reversed by anti-VEGF antibody and SU5614 (catalytic inhibitor of VEGFR). Furthermore, addition of tryptase to HDMECs caused a significant increase of mRNA and protein levels of VEGF and its receptors (Flt-1 and Flk-1) by Real-time RT-PCR and Western blot, respectively. These results strongly suggest an important role of VEGF on the permeability enhancement induced by tryptase, which may lead to novel means of controlling allergic reaction in skin

Involvement of potential pathways in malignant transformation from Oral Leukoplakia to Oral Squamous Cell Carcinoma revealed by proteomic analysis

<p>Abstract</p> <p>Background</p> <p>Oral squamous cell carcinoma (OSCC) is one of the most common forms of cancer associated with the presence of precancerous oral leukoplakia. Given the poor prognosis associated with oral leukoplakia, and the difficulties in distinguishing it from cancer lesions, there is an urgent need to elucidate the molecular determinants and critical signal pathways underlying the malignant transformation of precancerous to cancerous tissue, and thus to identify novel diagnostic and therapeutic target.</p> <p>Results</p> <p>We have utilized two dimensional electrophoresis (2-DE) followed by ESI-Q-TOF-LC-MS/MS to identify proteins differentially expressed in six pairs of oral leukoplakia tissues with dysplasia and oral squamous cancer tissues, each pair was collected from a single patient. Approximately 85 differentially and constantly expressed proteins (> two-fold change, P < 0.05) were identified, including 52 up-regulated and 33 down-regulated. Gene ontological methods were employed to identify the biological processes that were over-represented in this carcinogenic stage. Biological networks were also constructed to reveal the potential links between those protein candidates. Among them, three homologs of proteosome activator PA28 a, b and g were shown to have up-regulated mRNA levels in OSCC cells relative to oral keratinocytes.</p> <p>Conclusion</p> <p>Varying levels of differentially expressed proteins were possibly involved in the malignant transformation of oral leukoplakia. Their expression levels, bioprocess, and interaction networks were analyzed using a bioinformatics approach. This study shows that the three homologs of PA28 may play an important role in malignant transformation and is an example of a systematic biology study, in which functional proteomics were constructed to help to elucidate mechanistic aspects and potential involvement of proteins. Our results provide new insights into the pathogenesis of oral cancer. These differentially expressed proteins may have utility as useful candidate markers of OSCC.</p

Hyalinizing clear cell carcinoma of salivary gland: a clinicopathological study of 8 cases

Background and purpose: Hyalinizing clear cell carcinoma (HCCC) of salivary gland is a rare tumor with low-grade malignancy, which usually occurs in minor salivary glands. Due to its rarity, the tumor type is not well known to pathologists and misdiagnosis frequently occurred. The aim of this study was to investigate the histologic, immunophenotypic and molecular features of HCCC. Methods: Eight cases of salivary gland HCCC diagnosed at the Department of Pathology, Fudan University Shanghai Cancer Center from January 2015 to October 2019 were collected. Clinicopathologic characteristics were analyzed, and fluorescence in situ hybridization (FISH) assay was used to detect EWSR1 translocation in tumor tissue. Diagnostic criteria and differential diagnosis were summarized, with a review of the literature. Results: All patients were female, aged 26 to 68 years, and the tumor locations included the oral cavity, nasopharynx, parotid gland and other sites of head and neck. Microscopically, the tumors consisted mainly of clear cells and eosinophilic cells with variable proportions, arranged in nests, sheets and trabeculae. In 1 case, the tumor was composed almost entirely of eosinophilic cells; in 6 cases, obvious nuclear pseudo-inclusion bodies were seen; in 1 case, neoplastic cells were connected to the surface squamous epithelium; in 1 case, the glandular structure was seen in some areas of the tumor; in 3 cases, a sheath of lymphocyte was formed around the tumor nests; in 7 cases, there was a sclerosing or hyalinizing stromal reaction, showing desmoplastic changes; and 1 case featured stoma with myxoid changes. There was no definite keratinization or necrosis in all tumors, and mitotic figures were generally rare. Immunohistochemical staining showed that tumor cells of 8 cases were diffusely positive for AE1/AE3 protein, 7 cases expressed P63, and 7 cases focally expressed low molecular weight keratin CK7 or CAM5.2, however, S-100, calponin, PAX-8 and CD10 were all negative. All tumors showed low proliferative activity, with the Ki-67 proliferation index less than 5%. FISH test revealed EWSR1 translocation in all 8 cases. All patients demonstrated no recurrence or metastasis during the follow up ranging 4-50 months. Conclusions: HCCC of salivary gland is a low-grade malignancy occurring mainly in minor salivary glands, with characteristic histological and molecular features. This cancer type needs to be distinguished with many morphologic mimics of salivary gland. Most cases with salivary HCCC feature a good prognosis

Syngeneic animal models of tobacco-associated oral cancer reveal the activity of in situ anti-CTLA-4.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Tobacco use is the main risk factor for HNSCC, and tobacco-associated HNSCCs have poor prognosis and response to available treatments. Recently approved anti-PD-1 immune checkpoint inhibitors showed limited activity (≤20%) in HNSCC, highlighting the need to identify new therapeutic options. For this, mouse models that accurately mimic the complexity of the HNSCC mutational landscape and tumor immune environment are urgently needed. Here, we report a mouse HNSCC model system that recapitulates the human tobacco-related HNSCC mutanome, in which tumors grow when implanted in the tongue of immunocompetent mice. These HNSCC lesions have similar immune infiltration and response rates to anti-PD-1 (≤20%) immunotherapy as human HNSCCs. Remarkably, we find that &gt;70% of HNSCC lesions respond to intratumoral anti-CTLA-4. This syngeneic HNSCC mouse model provides a platform to accelerate the development of immunotherapeutic options for HNSCC

A clinical evaluation of amlexanox oral adhesive pellicles in the treatment of recurrent aphthous stomatitis and comparison with amlexanox oral tablets: a randomized, placebo controlled, blinded, multicenter clinical trial

<p>Abstract</p> <p>Background</p> <p>Amlexanox has been developed as a 5 percent topical oral paste for the treatment of patients with recurrent aphthous stomatitis (RAS) in most European countries. However, it is not yet available in China and has not been generally accepted in clinical treatment. The aim of this study was to explore the effectiveness of amlexanox oral adhesive pellicles in the treatment of minor recurrent aphthous ulcers, and compare the results with those of amlexanox oral adhesive tablets in order to analyse the difference between the two dosage forms of amlexanox.</p> <p>Methods</p> <p>We performed a randomized, blinded, placebo-controlled, parallel, multicenter clinical study. A total of 216 patients with minor recurrent aphthous ulcers (MiRAU) were recruited and randomized to amlexanox pellicles or placebo pellicles. Pellicles were consecutively applied four times per day, for five days. The size and pain level of ulcers were measured and recorded on treatment days 0, 4 and 6. Finally, the results were compared with those of our previous 104 cases treated with amlexanox tablets.</p> <p>Results</p> <p>Amlexanox oral adhesive pellicles significantly reduced ulcer size (P= 0.017 for day 4, P=0.038 for day 6) and alleviated ulcer pain (P=0.021 for day 4, P=0.036 for day 6). No significant difference was observed in the treatment effectiveness between the pellicle and tablet form of amlexanox.</p> <p>Conclusions</p> <p>Amlexanox oral adhesive pellicles are as effective and safe as amlexanox oral adhesive tablets in the treatment of MiRAU for this Chinese cohort. However, pellicles seem to be more comfortable to use when compared with the dosage form of tablets. Therefore, in clinical practice, amlexanox oral adhesive pellicles may be a better choice for RAS patients.</p> <p>Trials registration</p> <p>Nederlands Trial Register NTR1727.</p