Search

In this paper, we describe a case-study exploring the use of 600 MW of power from New Zealand's Manapouri Power Station to produce hydrogen for export via water electrolysis. Three H 2 carriers were considered: liquid H 2 , ammonia, and toluene hydrogenation/methylcyclohexane dehydrogenation. Processes were simulated in Aspen's HYSYS for each of the carriers to determine their associated energy and annualised capital expenditure costs. We found that the total capital investment for all carriers was surprisingly consistent, but with quite different splits between the electrolysis and carrier formation plants. Based on our analysis the energy availability for liquid H 2 ranged from 53.9 to 60.7% depending on the energy cost associated with cryogenic H 2 liquefaction. The energy availability for liquid ammonia was 37.5% after conversion back to H 2 , or 53.6% if the ammonia can be used directly as a fuel. For toluene/methylcyclohexane the energy availability was 41.2%. The total of the electricity and annualised capital costs per kg of H 2 ranged from NZ$5.63 to NZ$6.43 for liquid H 2 , NZ$6.24 to NZ$8.91 for ammonia and was NZ$7.86 for toluene/methylcyclohexane, using a net electricity cost of NZ$70/MWh. The cost of hydrogen (or energy in the case of direct use ammonia) was more strongly influenced by the efficiency of energy retention than on capital investment, as the electricity costs contributed approximately two thirds of total costs. In the long-term, liquid hydrogen looks to be the most versatile H 2 carrier, but significant infrastructure investment is required. • Capital costs of large-scale hydrogen carrier formation plants estimated. • Liquid hydrogen, ammonia and methylcyclohexane carrier systems compared. • Combined cost of electrolysis and carrier formation plants similar: from NZ$1.85 to $2.04 billion for a power envelope of 600 MW. • Energy efficiency of carrier system determines final cost of hydrogen energy. • Efficiency of ammonia comparable to liquid hydrogen, but only for direct use. [ABSTRACT FROM AUTHOR]

Background: Clinicians need improved tools to better identify nonacute heart failure with preserved ejection fraction (HFpEF)., Objectives: The purpose of this study was to derive and validate circulating microRNA signatures for nonacute heart failure (HF)., Methods: Discovery and validation cohorts (N = 1,710), comprised 903 HF and 807 non-HF patients from Singapore and New Zealand (NZ). MicroRNA biomarker panel discovery in a Singapore cohort (n = 546) was independently validated in a second Singapore cohort (Validation 1; n = 448) and a NZ cohort (Validation 2; n = 716)., Results: In discovery, an 8-microRNA panel identified HF with an area under the curve (AUC) 0.96, specificity 0.88, and accuracy 0.89. Corresponding metrics were 0.88, 0.66, and 0.77 in Validation 1, and 0.87, 0.58, and 0.74 in Validation 2. Combining microRNA panels with N-terminal pro-B-type natriuretic peptide (NT-proBNP) clearly improved specificity and accuracy from AUC 0.96, specificity 0.91, and accuracy 0.90 for NT-proBNP alone to corresponding metrics of 0.99, 0.99, and 0.93 in the discovery and 0.97, 0.96, and 0.93 in Validation 1. The 8-microRNA discovery panel distinguished HFpEF from HF with reduced ejection fraction with AUC 0.81, specificity 0.66, and accuracy 0.72. Corresponding metrics were 0.65, 0.41, and 0.56 in Validation 1 and 0.65, 0.41, and 0.62 in Validation 2. For phenotype categorization, combined markers achieved AUC 0.87, specificity 0.75, and accuracy 0.77 in the discovery with corresponding metrics of 0.74, 0.59, and 0.67 in Validation 1 and 0.72, 0.52, and 0.68 in Validation 2, as compared with NT-proBNP alone of AUC 0.71, specificity 0.46, and accuracy 0.62 in the discovery; with corresponding metrics of 0.72, 0.44, and 0.57 in Validation 1 and 0.69, 0.48, and 0.66 in Validation 2. Accordingly, false negative (FN) (81% Singapore and all NZ FN cases were HFpEF) as classified by a guideline-endorsed NT-proBNP ruleout threshold, were correctly reclassified by the 8-microRNA panel in the majority (72% and 88% of FN in Singapore and NZ, respectively) of cases., Conclusions: Multi-microRNA panels in combination with NT-proBNP are highly discriminatory and improved specificity and accuracy in identifying nonacute HF. These findings suggest potential utility in the identification of nonacute HF, where clinical assessment, imaging, and NT-proBNP may not be definitive, especially in HFpEF., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Heart failure (HF) with preserved ejection fraction (EF) accounts for a substantial proportion of cases of HF, and to date no treatments have clearly improved outcome. There are also little data comparing HF cohorts of differing ethnicity within the Asia-Pacific region., Methods: The Singapore Heart Failure Outcomes and Phenotypes (SHOP) study and Prospective Evaluation of Outcome in Patients with Heart Failure with Preserved Left Ventricular Ejection Fraction (PEOPLE) study are parallel prospective studies using identical protocols to enroll patients with HF across 6 centers in Singapore and 4 in New Zealand. The objectives are to determine the relative prevalence, characteristics, and outcomes of patients with HF and preserved EF (EF ≥50%) compared with those with HF and reduced EF, and to determine initial data on ethnic differences within and between New Zealand and Singapore. Case subjects (n = 2,500) are patients hospitalized with a primary diagnosis of HF or attending outpatient clinics for management of HF within 6 months of HF decompensation. Control subjects are age- and gender-matched community-based adults without HF from Singapore (n = 1,250) and New Zealand (n = 1,073). All participants undergo detailed clinical assessment, echocardiography, and blood biomarker measurements at baseline, 6 weeks, and 6 months, and are followed over 2 years for death or hospitalization. Substudies include vascular assessment, cardiopulmonary exercise testing, retinal imaging, and cardiac magnetic resonance imaging., Conclusions: The SHOP and PEOPLE studies are the first prospective multicenter studies defining the epidemiology and interethnic differences among patients with HF in the Asia-Oceanic region, and will provide unique insights into the pathophysiology and outcomes for these patients., (Copyright © 2013 Elsevier Inc. All rights reserved.)