252,493 research outputs found
Practical application of on-line partial discharge monitoring technique on 500kV shunt reactor
No full textConsidering the damage mechanism of oil-impregnated paper insulation in power transformers, shunt reactors and other high voltage electrical apparatus caused by partial discharge, a concept of “destructive partial discharge” is introduced in this paper. The intensity of this discharge is regarded as several thousands pico-coulomb (pC) and may cause the insulation a fatal damage. An oil-paper insulation is usually able to withstand this type of partial discharge for a period of time prior to failure. This provides engineers a time window to detect it. This paper describes an on-line partial discharge monitoring system for 500kV shunt reactors. The commission results from 3 single-phase shunt reactors either connected or disconnected to the grid showed that the on-line partial discharge detecting system has a high noise immunising ability. Two years later after the installation, a pre-warning signal was received from one shunt reactor indicating the existence of an intermittent discharge. The acoustic emission system located its position at the low end of the high voltage bushing in the oil. Dissolved gasses analysis (DGA) in the oil suggested the presence of partial discharge, as acetylene (C2H2) was as high as 20ppm. PD activity was further confirmed by a physical examination on the reactor
Pharmacoeconomic analysis of adjuvant oral capecitabine vs intravenous 5-FU/LV in Dukes' C colon cancer: the X-ACT trial
No full textOral capecitabine (Xeloda<sup>®</sup>) is an effective drug with favourable safety in adjuvant and metastatic colorectal cancer. Oxaliplatin-based therapy is becoming standard for Dukes' C colon cancer in patients suitable for combination therapy, but is not yet approved by the UK National Institute for Health and Clinical Excellence (NICE) in the adjuvant setting. Adjuvant capecitabine is at least as effective as 5-fluorouracil/leucovorin (5-FU/LV), with significant superiority in relapse-free survival and a trend towards improved disease-free and overall survival. We assessed the cost-effectiveness of adjuvant capecitabine from payer (UK National Health Service (NHS)) and societal perspectives. We used clinical trial data and published sources to estimate incremental direct and societal costs and gains in quality-adjusted life months (QALMs). Acquisition costs were higher for capecitabine than 5-FU/LV, but higher 5-FU/LV administration costs resulted in 57% lower chemotherapy costs for capecitabine. Capecitabine vs 5-FU/LV-associated adverse events required fewer medications and hospitalisations (cost savings £3653). Societal costs, including patient travel/time costs, were reduced by >75% with capecitabine vs 5-FU/LV (cost savings £1318), with lifetime gain in QALMs of 9 months. Medical resource utilisation is significantly decreased with capecitabine vs 5-FU/LV, with cost savings to the NHS and society. Capecitabine is also projected to increase life expectancy vs 5-FU/LV. Cost savings and better outcomes make capecitabine a preferred adjuvant therapy for Dukes' C colon cancer. This pharmacoeconomic analysis strongly supports replacing 5-FU/LV with capecitabine in the adjuvant treatment of colon cancer in the UK
Combination of 5-FU and MDM2/4 peptide inhibitors as a promising strategy to enhance 5-FU induced nucleolar stress.
No full textThe inactivation of tumor suppressor p53 is crucial for tumor onset and progression. Half of colorectal cancer cases carry wild-type p53 that is inactivated by the overexpression of MDM2 and MDM4, the main negative regulators of p53 activity [1]. Hence, the reactivation of p53 by inhibiting MDM2/4-p53 interaction represents a useful strategy to enhance the p53-depemdent cancer cell response to chemotherapeutic drugs. Recently, it has been demonstrated that 5-Fluoruracil (5-FU), the standard first-line treatment for colorectal cancer therapy, exerts its cytotoxic effect through the activation of p53-dependent nucleolar stress response [2].
It has been recently discovered that Pep3, a 12-mer peptide, is able to disrupt the MDM2/4 heterodimer producing a more efficient p53 reactivation [3]. In this study, we developed a library of sixteen Pep3 derivatives with sequence lengths ranging from 5- to 8-mer. Intriguingly, the newly truncated peptides displayed lower IC50 values than Pep3; among which the most active peptides were VLP-13 and VLP-24. We incorporated them, alone or in association with 5-FU, in novel biodegradable nanoparticles, and we analyzed their cytotoxic activity against p53 proficient colon cancer cells. We found that the cytotoxic activity of VLP-24 was higher than VLP-13 alone or in association with 5-FU. Notably, the combined treatment with 5-FU and VLP-24 caused a significant unbalance of ribosomal RNA precursor levels associated to a strong increase of p53 and p21 expression levels leading to the activation of apoptosis. In conclusion, our data demonstrate that VLP-24 is a promising strategy to enhance 5-FU mediated activation of p53-dependent nuclear stress response.
[1] Liebl MC et al. Cancers (2021); 13, 2125.
[2] Pecoraro A et al. Int J Mol Sci. (2021); 22, 5496.
[3] Pellegrino M et al. Cancer Res. (2015); 75; 4560-72
Influence of ac ageing on space charge dynamics in LDPE
No full textPolymeric materials have been widely used as insulation in power industry due to their excellent electrical properties. However, these properties deteriorate in time irreversibly when the material is subjected to electric stress. Although space charge is believed to play an important role in ac ageing, exact mechanisms are poorly understood due to very limited experimental data. In the present work efforts have been made to investigate the influence of ac ageing on space charge dynamics in low-density polyethylene (LDPE). LDPE films with 200mm were aged at 50 kV/mm at 50 Hz for various times at ambient temperature. Space charge dynamics in the samples prior to and after ageing were monitored using the pulsed electroacoustic (PEA) technique under dc electric stress. The results indicate that there is a significant amount of homocharge accumulation in the unaged sample due to charge injection. These injected charges are the captured by the deep traps originated from the interface between crystalline and amorphous regions in LDPE. Ageing under ac condition does not necessarily lead to an increase in amount of charge in the bulk but leads to an increase in mobility of charge carriers. Chemical analysis by infrared spectroscope (FTIR) reveals there are chemical changes taken place in the bulk of the material after ac ageing. It is believed that the chemical changes introduce shallow traps which promote the movement of charge carriers in the bulk. Consequently, the injected charges spread across the sample
Asuridia kishidai Wu & Fu 2013, sp. nov.
No full textAsuridia kishidai Wu & Fu, sp. nov. (Figs 7, 8, 13, 14, 16) Asuridia rubripennis: Fu & Tzuoo, 2004: 134, pl. 54: 21, nec Inoue, 1988. Type material. Holotype. Male. TAIWAN. Hualien County, Jinma Tunnel, 2450 m, 16-VI-2012, leg. C. M. Fu (coll. NMNS). Paratypes. TAIWAN. 1 male, 1 female, from the same collecting locality, 12-VII-2009, leg. L. C. Shih (coll. ESRI); 1 male, Taichung County, Anmashan, 2100 m, 30-VI-1997, leg. C. M. Fu; 1 male, Nantou County, Meifeng, 2,100 m, 29-VII-1984, leg. B. S. Chang (coll. NMNS); 1 male, Nantou County, Biluxi, 2100 m, 23-VI-2009, leg. Y. M. Chen (coll. TFRI) Diagnosis. This species is similar to A. inouei sp. nov., their differences being compared in the diagnosis part of the two preceding species. Description. Adult (Figs 7,8). Wingspan 25–26 in males (n= 5); 26 in females (n= 1). Antenna ciliate, male with a pair of long bristles on each segment, bristles as long as the diameter of shaft in median region. Head, thorax rosy-red, abdomen pinkish-ochreous. Forewing apex pointed; outer margin smoothly excurved; ground coloration rosy-red, costal margin black; transversal lines prominent, dark grey, antemedial line double peaked, medial line stout, nearly straight, postmedial line curved outward from costal margin to CuA1, then becoming straight towards tornus; submarginal striae long, prominent; marginal scales dark grey. Hindwing reddish ochreous; medial line light grey, wide, indistinct; marginal scales dark ochreous. Male genitalia (Figs 13,14). Uncus sclerotized, slightly curved downward at medial part, apex tapering; tegumen long and narrow; vinculum short; saccus U-shaped; juxta sclerotized, plate-like; valva sclerotized, costal margin protruded at medial part, distal part round, one ventral process arising from ¾ part of costal margin from base, apex round with dense spinose tufts; sacculus stout, one ventral process arising from ⅓ part from base with dense, stout spinose tufts at apex, distal part of sacculus process hook-like and strongly sclerotized. Aedeagus stout, spinose patches arising from two lateral sides of manica; dorsal part of vesica scobinate, basal part expanded, gradually tapering distally, two moderate spinose patches and a weak sclerotized plate arising from dorsal part of vesica. Female genitalia (Fig. 16). Ovipositor lobes membranous with short hair-like setae; apophyses elongated, length of anterior and posterior ones equal. Ostium bursae sclerotized, stout, ventral part strongly and widely incised (V-shaped); ductus bursae very short, sclerotized; corpus bursae sac-like, posterior ⅓ part covered densely with short spinules and scobination, this covering extends toward fundus bursae at left side; ductus seminalis arising from medial part of corpus bursae. Etymology. Dedicated to Yasunori Kishida, an expert on Asiatic arctiine moths. Notes. This species is endemic to Taiwan, and occurs in mid-elevations in broad-leaved forests in central Taiwan. It is probably univoltine, the adults are on the wing in June and July. The immature stages remain unknown.Published as part of Wu, Shipher & Fu, Chien-Ming, 2013, The genus Asuridia Hampson, 1900 in Taiwan, with descriptions of two new species (Erebidae, Arctiinae, Lithosiini), pp. 595-599 in Zootaxa 3737 (5) on pages 598-599, DOI: 10.11646/zootaxa.3737.5.7, http://zenodo.org/record/527054
Electric field determination of polymeric dc power cable in the presence of space charge
No full textSpace charge in polymeric power cables has been previously measured by the pulsed electroacoustic (PEA) technique and its influence on electric field distribution has been estimated assuming that the conductivity is independent of electric field. In this paper we proposed a method of determining electric field distribution considering the influence of the effect of electric field on the conductivity. The cable insulation is divided into thin layers with different conductivities and space charge present in the each layer is viewed as the consequence caused by difference in conductivity. Based on the hopping conduction mechanisms, it is possible to compute electric field distribution across the cable insulation. Compared with the electric field distribution without considering change in conductivity, the new proposed method shows reduction at the maximum electric field. However, the position of the maximum electric field shifts depending on space charge distribution
Space charge measurements in polymer insulated power cables using flat ground electrode PEA system
No full textThis paper describes the data processing methods used to accurately determine the space charge and electric stress distributions in dc power cables using the Pulsed Electro-Acoustic (PEA) system. Due to the coaxial geometry and the thick walled insulation of high voltage cables, factors such as divergence, attenuation and dispersion of the propagated acoustic pressure wave in the PEA can strongly influence the resultant measurements. The above factors are taken into account ensuring accurate measurements to be made. Most importantly, a method is presented to determine the electric stress profile across the insulation due to both the divergent applied field and that as a consequence of trapped charge in the bulk of the insulating material. Results of space charge measurements and the corresponding derived electric stress distributions in XLPE dc cables are presented
“Mirror Image Effect” Space Charge Distribution in XLPE Power Cable under Opposite Stressing Voltage Polarity
No full textThe paper presents space charge distributions under opposite voltage polarities in full size cross-linked polyethylene power cables using the pulsed electro-acoustic technique. Under both positive and negative polarities, space charge distributions possess similar profiles but opposite polarities. A similar phenomenon had been reported previously in plaque samples and was termed the “mirror image effect”. By comparing the results between cables treated by degassing under different conditions, the paper concludes that the “mirror image” charge distribution is mainly attributed to a bulk effect within the volume of the insulation, whilst electron transfer by tunneling through an electrode/insulator interface contributes to the generation of homo “mirror image” close to the electrodes
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