Matrix Converter for More Electric Aircraft

This proposed chapter discusses three methods that do not allow regenerative power from the matrix converter (MC) motor drive onto the aircraft power supply. According to aerospace power quality specifications, the regenerative power must be dissipated in the drive itself to avoid instability problem in aircraft power supply. These are bidirectional switch (BDS) method, input power clamp (IPC) method, and standard clamp circuit (SCC) method for aerospace applications. To identify regeneration in a matrix converter drive, two novel techniques are proposed. These are power comparison technique (PC) and input voltage reference technique (IVR). In both techniques, output power of MC and direction of speed, these factors are used to detect regeneration in MC drive. The electrical braking is important in many aerospace applications such as surface actuation and air-to-air (in-flight) refueling system. Therefore, the inherent regeneration capability of the matrix converter drive is not desirable for aerospace applications so it has to be avoided. The proposed methods are demonstrated through detailed simulation results and experimental verification. In order to prove the proposed methods with novel techniques, a 7.5-kW matrix converter fed 4-kW induction motor (IM) with inertial load has experimentally implemented. The obtained results using BDS method with PC technique proved avoiding regeneration with a matrix converter is feasible. This chapter is valuable for 150-kVA matrix converter for high-power application

Electrical braking in matrix converter for more electric aircraft: bi-directional switch and input power clamp methods

Current aircraft power quality specifications do not allow regeneration onto the power bus. Therefore, the inherent regeneration available from Matrix Converter (MC) is not desirable in More Electric Aircraft (MEA) aerospace applications. In this paper, novel methods to avoid regeneration from the Matrix Converters are proposed. The methods have been called the Bi-Directional Switch (BDS) method and the Input Power Clamp (IPC) method. Both methods are compared. The IPC method is considered an alternative to the Bi-Directional Switch (BDS) method and has a number of advantages discussed in the paper. To detect regeneration in Matrix Converters two techniques are proposed, the Power Comparison technique (PC) and the Input Voltage Reference technique (IVR). Experimental results from a prototype using 4 kW Induction Motor are presented

Avoiding regeneration with a matrix converter drive

Recently, the conventional Matrix Converter has been considered for aerospace applications because of its compactness in weight and size due to absence of a DC-Link capacitor. In addition the Matrix Converter is capable of producing a variable output voltage with unrestricted input and output frequency. This is useful in aerospace applications which require a wide range of input frequency, sometimes from 360 Hz to 900 Hz. These key features are only obtained from the Matrix Converter without using any large passive components. The Matrix Converter has an inherent regeneration capability. However, the avoidance of the regeneration may be vital in many aerospace applications, such as aircraft surface actuation systems. According to current aircraft power quality specifications regeneration is not allowed and must be dissipated with in the Matrix Converter drive itself. This thesis proposes two novel methods which allow regeneration from the Matrix Converter motor drive to be avoided. These are the Bi-Directional Switch (BDS) method and Input Power Clamp (IPC) method. In order to detect regeneration in the Matrix Converter motor drive two techniques are used. These are the Power Comparison (PC) technique and Input Voltage Reference (IVR) technique. Finally, to validate the proposed methods a Matrix Converter has been designed and built with a Regeneration Control Circuit (RCC). Indirect vector control is used to control 4.0 kW Induction Motor. Based on the simulation results and experimental results using the BDS method to avoid regeneration with a Matrix Converter is feasible

Avoiding regeneration with a matrix converter drive

Recently, the conventional Matrix Converter has been considered for aerospace applications because of its compactness in weight and size due to absence of a DC-Link capacitor. In addition the Matrix Converter is capable of producing a variable output voltage with unrestricted input and output frequency. This is useful in aerospace applications which require a wide range of input frequency, sometimes from 360 Hz to 900 Hz. These key features are only obtained from the Matrix Converter without using any large passive components. The Matrix Converter has an inherent regeneration capability. However, the avoidance of the regeneration may be vital in many aerospace applications, such as aircraft surface actuation systems. According to current aircraft power quality specifications regeneration is not allowed and must be dissipated with in the Matrix Converter drive itself. This thesis proposes two novel methods which allow regeneration from the Matrix Converter motor drive to be avoided. These are the Bi-Directional Switch (BDS) method and Input Power Clamp (IPC) method. In order to detect regeneration in the Matrix Converter motor drive two techniques are used. These are the Power Comparison (PC) technique and Input Voltage Reference (IVR) technique. Finally, to validate the proposed methods a Matrix Converter has been designed and built with a Regeneration Control Circuit (RCC). Indirect vector control is used to control 4.0 kW Induction Motor. Based on the simulation results and experimental results using the BDS method to avoid regeneration with a Matrix Converter is feasible

Comparative evaluation of spinal anaesthesia with levobupivacaine and hyperbaric bupivacaine for caesarean section: A study of 60 cases

AIM & OBJECTIVES: This study was performed to compare the anesthetic efficacy and safety of two local anesthetic agents : hyperbaric bupivacaine and isobaric levobupivacaine, in patients undergoing elective caesarean section. METHODS AND MATERIALS: Sixty patients, ASA I-II, were randomized to receive an intrathecal injection of hyperbaric bupivacaine or isobaric levobupivacaine. Group B (n = 30) received 2 ml of Hyperbaric bupivacaine 5 mg/ml (10 mg). Group L (n = 30) received 2 ml of isobaric levobupivacaine 5 mg/ml (10 mg). The onset and duration of sensory and motor blockade, recovery parameters, hemodynamic changes and side effects for the two agents were compared. RESULTS: The time of onset of sensory block was faster in Group B(1.46 ± 0.50) when compared with Group L(2.0 ± 0.37). In Group B the time to two segment regression was prolonged (76.16 ± 13.86) when compared with Group L (68.43 ±12.96) and it is statistically significant. Duration of motor blockade was prolonged in Group B(132 ± 7.67) when compared with Group L (99 ± 9.13). Hemodynamic variables were more stable in Group L than Group B. Twelve patients in Group B had adverse effects when compared with seven patients in Group L. CONCLUSION: 0.5% Isobaric Levobupivacaine 10mg for intrathecal injection of caesarean section produces adequate sensory and motor blockade and stable hemodynamic parameters with minimum adverse effects than 0.5% hyperbaric bupivacaine 10mg. We concluded that isobaric Levobupivacaine is a better alternative for caesarean section

Standard clamp for regenerative braking in matrix converter drive: more electric aircraft

This paper describes a novel method for braking regeneration in the Matrix Converter (MC) drive is proposed, called Standard Clamp Circuit (SCC) method for More Electric Aircraft (MEA). In earlier publications, Bi-Directional Switch (BDS) method and Input Power Clamp (IPC) method with Power Comparison (PC) technique and Input Voltage Reference (IVR) technique for regenerative braking or electrical braking in the Matrix Converter drive have been discussed. The electrical braking is important in many aerospace applications such as surface actuation and Air to Air (in-flight) refueling system. Therefore, the inherent regeneration capability of the Matrix Converter drive is not desirable for aerospace applications so it has to be avoided. In contrast to earlier methods, the proposed SCC method is using the existing standard clamp circuit in the Matrix Converter drive. The proposed methods are demonstrated through detailed simulation results

Targeting EGF-receptor(s) - STAT1 axis attenuates tumor growth and metastasis through downregulation of MUC4 mucin in human pancreatic cancer.

Transmembrane proteins MUC4, EGFR and HER2 are shown to be critical in invasion and metastasis of pancreatic cancer. Besides, we and others have demonstrated de novo expression of MUC4 in ~70-90% of pancreatic cancer patients and its stabilizing effects on HER2 downstream signaling in pancreatic cancer. Here, we found that use of canertinib or afatinib resulted in reduction of MUC4 and abrogation of in vitro and in vivo oncogenic functions of MUC4 in pancreatic cancer cells. Notably, silencing of EGFR family member in pancreatic cancer cells decreased MUC4 expression through reduced phospho-STAT1. Furthermore, canertinib and afatinib treatment also inhibited proliferation, migration and survival of pancreatic cancer cells by attenuation of signaling events including pERK1/2 (T202/Y204), cyclin D1, cyclin A, pFAK (Y925) and pAKT (Ser473). Using in vivo bioluminescent imaging, we demonstrated that canertinib treatment significantly reduced tumor burden (P=0.0164) and metastasis to various organs. Further, reduced expression of MUC4 and EGFR family members were confirmed in xenografts. Our results for the first time demonstrated the targeting of EGFR family members along with MUC4 by using pan-EGFR inhibitors. In conclusion, our studies will enhance the translational acquaintance of pan-EGFR inhibitors for combinational therapies to combat against lethal pancreatic cancer

RNA-Based Therapies: A Cog in the Wheel of Lung Cancer Defense

Lung cancer (LC) is a heterogeneous disease consisting mainly of two subtypes, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), and remains the leading cause of death worldwide. Despite recent advances in therapies, the overall 5-year survival rate of LC remains less than 20%. The efficacy of current therapeutic approaches is compromised by inherent or acquired drug-resistance and severe off-target effects. Therefore, the identification and development of innovative and effective therapeutic approaches are critically desired for LC. The development of RNA-mediated gene inhibition technologies was a turning point in the field of RNA biology. The critical regulatory role of different RNAs in multiple cancer pathways makes them a rich source of targets and innovative tools for developing anticancer therapies. The identification of antisense sequences, short interfering RNAs (siRNAs), microRNAs (miRNAs or miRs), anti-miRs, and mRNA-based platforms holds great promise in preclinical and early clinical evaluation against LC. In the last decade, RNA-based therapies have substantially expanded and tested in clinical trials for multiple malignancies, including LC. This article describes the current understanding of various aspects of RNA-based therapeutics, including modern platforms, modifications, and combinations with chemo-/immunotherapies that have translational potential for LC therapies

MUC4 overexpression augments cell migration and metastasis through EGFR family proteins in triple negative breast cancer cells.

INTRODUCTION: Current studies indicate that triple negative breast cancer (TNBC), an aggressive breast cancer subtype, is associated with poor prognosis and an early pattern of metastasis. Emerging evidence suggests that MUC4 mucin is associated with metastasis of various cancers, including breast cancer. However, the functional role of MUC4 remains unclear in breast cancers, especially in TNBCs. METHOD: In the present study, we investigated the functional and mechanistic roles of MUC4 in potentiating pathogenic signals including EGFR family proteins to promote TNBC aggressiveness using in vitro and in vivo studies. Further, we studied the expression of MUC4 in invasive TNBC tissue and normal breast tissue by immunostaining. RESULTS: MUC4 promotes proliferation, anchorage-dependent and-independent growth of TNBC cells, augments TNBC cell migratory and invasive potential in vitro, and enhances tumorigenicity and metastasis in vivo. In addition, our studies demonstrated that MUC4 up-regulates the EGFR family of proteins, and augments downstream Erk1/2, PKC-γ, and FAK mediated oncogenic signaling. Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition. We also demonstrated in this study, for the first time, that knockdown of MUC4 was associated with reduced expression of EGFR and ErbB3 (EGFR family proteins) in TNBC cells, suggesting that MUC4 uses an alternative to ErbB2 mechanism to promote aggressiveness. We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue. CONCLUSIONS: MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo. Overall, our findings suggest that MUC4 mucin promotes invasive activities of TNBC cells by altering the expression of EGFR, ErbB2, and ErbB3 molecules and their downstream signaling

Molecular Implications of MUC5AC-CD44 Axis in Colorectal Cancer Progression and Chemoresistance

BACKGROUND: Differential expression of mucins has been associated with several cancers including colorectal cancer (CRC). In normal physiological conditions, secretory mucin MUC5AC is not expressed in the colonic mucosa, whereas its aberrant expression is observed during development of colon cancer and its precursor lesions. To date, the molecular mechanism of MUC5AC in CRC progression and drug resistance remains obscure. METHODS: MUC5AC expression was determined in colon tissue microarray by immunohistochemistry. A RNA interference and CRISPR/Cas9-mediated system was used to knockdown/knockout the MUC5AC in CRC cell lines to delineate its role in CRC tumorigenesis using in vitro functional assays and in vivo (sub-cutaneous and colon orthotopic) mouse models. Finally, CRC cell lines and xenograft models were used to identify the mechanism of action of MUC5AC. RESULTS: Overexpression of MUC5AC is observed in CRC patient tissues and cell lines. MUC5AC expression resulted in enhanced cell invasion and migration, and decreased apoptosis of CRC cells. MUC5AC interacted with CD44 physically, which was accompanied by the activation of Src signaling. Further, the presence of MUC5AC resulted in enhanced tumorigenesis and appearance of metastatic lesions in orthotopic mouse model. Additionally, up-regulation of MUC5AC resulted in resistance to 5-fluorouracil (5-FU) and oxaliplatin, and its knockout increased sensitivity to these drugs. Finally, we observed that up-regulation of MUC5AC conferred resistance to 5-FU through down-regulation of p53 and its target gene p21 and up-regulation of β-catenin and its target genes CD44 and Lgr5. CONCLUSION: Our findings suggest that differential expression of secretory mucin MUC5AC results in enhanced tumorigenesis and also confers chemoresistance via CD44/β-catenin/p53/p21 signaling