Cold start of a 5.5 MVA offshore transformer

SLIM® transformers are compact liquid-immersed transformers according to IEC 60076-14 and customised for typical applications such as on- and off-shore wind turbines. State of the art SLIM® wind turbine generator transformers (WTGT) have to operate in wind farms which are often located in remote locations with harsh conditions and sometime very low temperatures. After a few days of no wind the transformer can be cooled down to -30 °C or even -40 °C so these conditions need to be tested in advance. To ensure the reliability of CG Power System Belgium’s WTGT’s and the possibility to start in cold conditions, several tests were conducted in OWI-Lab’s large climatic test chamber. OWI-Lab’s test facility is the first public test centre in Europe that deals with extreme climatic tests of heavy machinery applications up to 150 tonnes with a special focus on wind turbine components. CG wants to prove that when WTGT’s have to operate in cold conditions, the internal cooling is still working properly. Due to higher viscosity at low temperature of the used cooling liquids, the natural convection cooling of the internal windings may be limited. According to the properties of the cooling liquid that is used inside the WTGT, it remains ‘liquid’ above -45 °C (pour point), but due to the high viscosity, the natural convection may be limited and there is a possibility that the initial losses generated inside the transformers’ windings cannot be evacuated fast enough. To verify if the natural convection starts, a full load cold start test was conducted at -30 °C to prove that the natural cooling of the internal windings starts immediately. During the cold start test the internal pressure and several temperatures such as the top oil were measured. Also a storage test was done at -40 ºC to check if the transformer can resist this ambient temperature. This storage test was conducted to prove that no leaks or other visual issues occurred on the tank and gaskets

Unique Cardiac Purkinje Fiber Transient-Outward Current Beta-Subunit Composition: A Potential Molecular Link to Idiopathic Ventricular Fibrillation.

Rationale: A chromosomal-haplotype producing cardiac overexpression of dipeptidyl peptidase-like protein-6 (DPP6) causes familial idiopathic ventricular fibrillation (IVF). The molecular basis of transient-outward current (Ito) in Purkinje fibers (PFs) is poorly understood. We hypothesized that DPP6 contributes to PF Ito and that its overexpression might specifically alter PF Ito-properties and repolarization. Objective: To assess the potential role of DPP6 in PF-Ito. Methods and Results: Clinical data in 5 IVF-patients suggested arrhythmia-origin in the PF conducting-system. PF and ventricular-muscle (VM) Ito had similar density, but PF Ito differed from VM in having tetraethylammonium-sensitivity and slower recovery. DPP6-overexpression significantly increased, whereas DPP6-kockdown reduced, Ito-density and tetraethylammonium-sensitivity in canine PF, but not VM-cells. The K+-channel interacting beta-subunit KChIP2, essential for normal expression of transient outward current (Ito) in VM, was weakly-expressed in human PFs, whereas DPP6 and frequenin (NCS-1) were enriched. Heterologous expression of Kv4.3 in Chinese hamster ovary (CHO)-cells produced very small Ito; Ito-amplitude was greatly enhanced by co-expression with KChIP2 or DPP6. Co expression of DPP6 with Kv4.3 and KChIP2 failed to alter Ito versus Kv4.3/KChIP2 alone, but DPP6 expression with Kv4.3 and NCS-1 (to mimic PF Ito-composition), greatly enhanced Ito versus Kv4.3/NCS-1 and recapitulated characteristic PF kinetic/pharmacological properties. A mathematical model of cardiac PF action potentials showed that Ito-enhancement can greatly accelerate PF repolarization. Conclusions: These results point to a previously-unknown central role of DPP6 in PF Ito, with DPP6 gain-of-function selectively enhancing PF-current, and suggest that a DPP6-mediated PF early repolarization syndrome might be a novel molecular paradigm for some forms of IVF

La Belgique peut gagner son indépendance énergétique en haute mer

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Arrhythmogenic right ventricular dysplasia/cardiomyopathy: Pathogenic desmosome mutations in index-patients predict outcome of family screening: Dutch arrhythmogenic right ventricular dysplasia/cardiomyopathy genotype-phenotype follow-up study

Background-: Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an autosomal dominant inherited disease with incomplete penetrance and variable expression. Causative mutations in genes encoding 5 desmosomal proteins are found in ≈50% of ARVD/C index patients. Previous genotype-phenotype relation studies involved mainly overt ARVD/C index patients, so follow-up data on relatives are scarce. Methods and Results-: One hundred forty-nine ARVD/C index patients (111 male patients; age, 49±13 years) according to 2010 Task Force criteria and 302 relatives from 93 families (282 asymptomatic; 135 male patients; age, 44±13 years) were clinically and genetically characterized. DNA analysis comprised sequencing of plakophilin-2 (PKP2), desmocollin-2, desmoglein-2, desmoplakin, and plakoglobin and multiplex ligation-dependent probe amplification to identify large deletions in PKP2. Pathogenic mutations were found in 87 index patients (58%), mainly truncating PKP2 mutations, including 3 cases with multiple mutations. Multiplex ligation-dependent probe amplification revealed 3 PKP2 exon deletions. ARVD/C was diagnosed in 31% of initially asymptomatic mutation-carrying relatives and 5% of initially asymptomatic relatives of index patients without mutation. Prolonged terminal activation duration was observed more than negative T waves in V1 to V3, especially in mutation-carrying relatives <20 years of age. In 45% of screened families, ≥1 affected relatives were identified (90% with mutations). Conclusions-: Pathogenic desmosomal gene mutations, mainly truncating PKP2 mutations, underlie ARVD/C in the majority (58%) of Dutch index patients and even 90% of familial cases. Additional multiplex ligation-dependent probe amplification analysis contributed to discovering pathogenic mutations underlying ARVD/C. Discovering pathogenic mutations in index patients enables those relatives who have a 6-fold increased risk of ARVD/C diagnosis to be identified. Prolonged terminal activation duration seems to be a first sign of ARVD/C in young asymptomatic relatives

Comprehensive dna analysis in dutch ARVD/C patients

Introduction: Familial Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) is an autosomal dominantly inherited disease with incomplete penetrance and highly variable expression. Mutations in genes encoding 5 desmosomal proteins and TMEM43 usually underlie ARVD/C. Aim: Comprehensive sequencing of all 6 genes in a large cohort of Dutch ARVD/C patients (pts) correlated with phenotypic characteristics. Methods: Inclusion of 109 ARVD/C pts (81 men, age 49±14 yrs) according to diagnostic Task Force Criteria (TFC). Clinical history and data on separate TFC were collected. DNA of all 109 pts was directly sequenced for mutations in desmosomal genes PKP2, DSC2, DSG2, DSP and JUP. In 81 cases TMEM43 was also analyzed. Pathogenic mutations were defined as DNA sequence variations disrupting conserved residues and not present in 200 ethnically-matched controls. Clinical characteristics were related to specific genes, type (truncating or not) and number of mutations. Results: In 63 of 109 pts (58%) single mutations were observed: 19 different PKP2 mutations in 57 cases, 5 in DSG2 and 1 in DSC2. Five more pts carried 2 mutations: in PKP2 and additionally in DSG2 (n=2), DSP (n=2) or TMEM43 (n=1). Mutations occurred equally in men and women. Phenotype variations were not related to gene or type of mutations. First arrhythmic event was at significantly younger age in pts with mutation than those without, and youngest in those 5 pts with bigenic involvement (mean age for 0, 1 and 2 mutations: 43, 34 and 21 yrs, resp). Also, between groups with 0, 1 and 2 mutations, occurrence of negative T waves in leads V1-3 (41, 80 and 100%, resp) and major structural abnormalities (46, 65 and 100% resp) was significantly different. Frequency of all other parameters was similar. Conclusions: In 68 of 109 (62%) Dutch ARVD/C patients pathogenic mutations were observed, mainly in PKP2, with multiple mutations in 5 cases. Mutation carriers more often had negative T waves in V1-3 and structural abnormalities. Moreover, they presented at younger age than patients without mutations; this age was even younger when multiple genes were affected. Screening of all relevant genes is needed for appropriate genotype-phenotype correlation

Genotype-phenotype analysis in arrhythmogenic right ventricular dysplasia/cardiomyopathy:Follow-up of a large series of dutch index-patients and family members

Background: In Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) causative mutations in genes encoding 5 desmosomal proteins or TMEM43 are found in the majority of patients. One of the primary clinical challenges in ARVD/C is timely diagnosis of those still asymptomatic. However, previous studies mainly involved overt ARVD/C index-patients. Follow-up data on relatives are scarce. Therefore, we sequenced all 6 genes in a large cohort of ARVD/C families and correlated results with clinical follow-up. Methods: 149 ARVD/C index-patients (111 men, age 49±13 years) according to 2010 Task Force Criteria (TFC) and 302 family members from 93 different families (282 asymptomatic, 135 men, age 44±13 years) were clinically and genetically analyzed. DNA analysis comprised sequencing of PKP2, DSC2, DSG2, DSP, JUP and TMEM43 and multiple ligation-dependent probe amplification (MLPA) to identify large PKP2 deletions. Results: Pathogenic mutations were found in 87 of 149 index-patients (58%): 90% PKP2 and multiple mutations in 4 cases. MLPA revealed 3 large PKP2 deletions (2%). Mutation carriers presented at younger age than non-carriers (35±12 vs 40±14 years; p=0.042). Familial cases were identified in 42 of 93 (45%) of index-patients with relatives screened: 90% with mutations. In total, 57 of 282 asymptomatic relatives (20%) showed signs of ARVD/C (age 47±18 years, 48 with mutations). See table 2. Terminal activation duration (TAD) 7ge;55ms occurred more than negative T waves in V1-3 (12 vs 7%), especially in those age