Thermodynamic analysis of high-temperature pumped thermal energy storage systems: Refrigerant selection, performance and limitations

[EN] One of the bottlenecks for a wider implementation of renewable energies is the development of efficient energy storage systems which can compensate for the intermittency of renewable energy sources. Pumped thermal energy storage (PTES) is a very recent technology that can be a promising site-independent alternative to pumped hydro energy storage or compressed air energy storage, without the corresponding geological and environmental restrictions. Accordingly, this paper presents a full thermodynamic analysis of a PTES system consisting of a high-temperature heat pump (HTHP), which drives an organic Rankine cycle (ORC) by means of an intermediate high-temperature thermal energy storage system (HT-TES). The latter combines both latent and sensible heat thermal energy storage sub-systems to maximize the advantage of the refrigerant subcooling. After validating the proposed model, several parametric studies have been carried out to assess the system performance using different refrigerants and configurations, under a wide range of source and sink temperatures. The results show that for a system that employs the same refrigerant in both the HTHP and ORC, and for a latent heat thermal energy storage system at 133 degrees C, R-1233zd(E) and R-1234ze(Z) present the best performance. Among all the cases studied with a latent heat thermal energy storage system at 133 degrees C, the best system performance, also considering the impact on the environment, has been achieved employing R-1233zd(E) in the HTHP and Butene in the ORC. Such a system can theoretically reach a power ratio of 1.34 under HTHP source and ORC sink temperatures of 100 and 25 degrees C, respectively. 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Triticum durum metallothionein: isolation of the gene and structural characterization of the protein using solution scattering and molecular modeling

A novel gene sequence, with two exons and one intron, encoding a metallothionein (MT) has been identified in durum wheat Triticum durum cv. Balcali85 genomic DNA. Multiple alignment analyses on the cDNA and the translated protein sequences showed that T. durum MT (dMT) can be classified as a type 1 MT. dMT has three Cys-X-Cys motifs in each of the N- and C-terminal domains and a 42-residue-long hinge region devoid of cysteines. dMT was overexpressed in Escherichia coli as a fusion protein (GSTdMT), and bacteria expressing the fusion protein showed increased tolerance to cadmium in the growth medium compared with controls. Purified GSTdMT was characterized by SDS- and native-PAGE, size exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. It was shown that the recombinant protein binds 4 ± 1 mol of cadmium/mol of protein and has a high tendency to form stable oligomeric structures. The structure of GSTdMT and dMT was investigated by synchrotron x-ray solution scattering and computational methods. X-ray scattering measurements indicated a strong tendency for GSTdMT to form dimers and trimers in solution and yielded structural models that were compatible with a stable dimeric form in which dMT had an extended conformation. Results of homology modeling and ab initio solution scattering approaches produced an elongated dMT structure with a long central hinge region. The predicted model and those obtained from x-ray scattering are in agreement and suggest that dMT may be involved in functions other than metal detoxification

Disabling knee pain – another consequence of obesity: Results from a prospective cohort study

BACKGROUND: Obesity is linked to knee osteoarthritis (OA) and knee pain. These are disabling problems that are more prevalent in older adults. No prospective study has estimated the impact of excess weight avoidance on the occurrence of knee pain in the general older population. The aim of this study was to investigate the influence of overweight and obesity on the onset and progression of knee pain and disability in older adults living in the community. METHODS: A prospective cohort study of people aged 50 and over registered with three general practices in North Staffordshire, UK. 5784 people who had responded to a survey in March 2000 were mailed a follow-up questionnaire in March 2003. The main outcome measures were self-reported knee pain and severe knee pain and disability at 3 years measured by the Western Ontario and McMaster Universities Osteoarthritis index. RESULTS: Adjusted response to follow-up was 75%. Among responders with no knee pain at baseline, obesity predicted onset of severe knee pain (relative risk 2.8; 95% CI 1.8, 4.5 compared to normal body mass index (BMI) category). Considering overweight and obese categories together, 19% of new cases of severe knee pain over a 3-year period could potentially be avoided by a one-category shift downwards in BMI; this includes almost half of the new cases that arose in the obese group. CONCLUSION: Obesity accounts for a substantial proportion of severe disabling knee pain. As knee pain is a common disabling condition in older adults living in the community, effective public health interventions about avoidance of excess weight could have a major impact on future lower limb disability in older adults

Evaluation of lifestyle interventions to treat elevated cardiometabolic risk in primary care (E-LITE): a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Efficacy research has shown that intensive individual lifestyle intervention lowers the risk for developing type 2 diabetes mellitus and the metabolic syndrome. Translational research is needed to test real-world models of lifestyle interventions in primary care settings.</p> <p>Design</p> <p>E-LITE is a three-arm randomized controlled clinical trial aimed at testing the feasibility and potential effectiveness of two lifestyle interventions: information technology-assisted self-management, either alone or in combination with care management by a dietitian and exercise counselor, in comparison to usual care. Overweight or obese adults with pre-diabetes and/or metabolic syndrome (n = 240) recruited from a community-based primary care clinic are randomly assigned to one of three treatment conditions. Treatment will last 15 months and involves a three-month intensive treatment phase followed by a 12-month maintenance phase. Follow-up assessment occurs at three, six, and 15 months. The primary outcome is change in body mass index. The target sample size will provide 80% power for detecting a net difference of half a standard deviation in body mass index at 15 months between either of the self-management or care management interventions and usual care at a two-sided α level of 0.05, assuming up to a 20% rate of loss to 15-month follow-up.</p> <p>Secondary outcomes include glycemic control, additional cardiovascular risk factors, and health-related quality of life. Potential mediators (e.g., treatment adherence, caloric intake, physical activity level) and moderators (e.g., age, gender, race/ethnicity, baseline mental status) of the intervention's effect on weight change also will be examined.</p> <p>Discussion</p> <p>This study will provide objective evidence on the extent of reductions in body mass index and related cardiometabolic risk factors from two lifestyle intervention programs of varying intensity that could be implemented as part of routine health care.</p> <p>Trial registration</p> <p>NCT00842426</p

Differential Scanning Fluorometry Signatures as Indicators of Enzyme Inhibitor Mode of Action: Case Study of Glutathione S-Transferase

Differential scanning fluorometry (DSF), also referred to as fluorescence thermal shift, is emerging as a convenient method to evaluate the stabilizing effect of small molecules on proteins of interest. However, its use in the mechanism of action studies has received far less attention. Herein, the ability of DSF to report on inhibitor mode of action was evaluated using glutathione S-transferase (GST) as a model enzyme that utilizes two distinct substrates and is known to be subject to a range of inhibition modes. Detailed investigation of the propensity of small molecule inhibitors to protect GST from thermal denaturation revealed that compounds with different inhibition modes displayed distinct thermal shift signatures when tested in the presence or absence of the enzyme's native co-substrate glutathione (GSH). Glutathione-competitive inhibitors produced dose-dependent thermal shift trendlines that converged at high compound concentrations. Inhibitors acting via the formation of glutathione conjugates induced a very pronounced stabilizing effect toward the protein only when GSH was present. Lastly, compounds known to act as noncompetitive inhibitors exhibited parallel concentration-dependent trends. Similar effects were observed with human GST isozymes A1-1 and M1-1. The results illustrate the potential of DSF as a tool to differentiate diverse classes of inhibitors based on simple analysis of co-substrate dependency of protein stabilization

Pore Volume and Porosity Changes under Uniaxial Strain Conditions

Expressions for the changes that occur in the pore volume and the porosity of a porous rock, due to changes in the pore pressure, overburden stress, and temperature, are derived within the context of the linearised theory of poroelasticity. The resulting expressions are compared to the commonly used equations proposed by Palmer and Mansoori, and it is shown that their expressions are consistent with the exact expressions if their factor f is identified with (1+ν)/3(1−ν)(1+ν)/3(1−ν) , where νν is the Poisson’s ratio of the porous rock. Finally, the first derivation is given, within the context of the fully coupled linearised theory of poroelasticity, that under uniaxial strain, the partial differential equation that governs the evolution of the pore pressure is a pure diffusion equation, with a total compressibility term that (exactly) equals the sum of the fluid compressibility and the uniaxial pore volume compressibility

The role of ligand efficiency metrics in drug discovery

The judicious application of ligand or binding efficiencies, which quantify the molecular properties required to gain binding affinity for a drug target, is gaining traction in the selection and optimisation of fragments, hits, and leads. Retrospective analysis of recently marketed oral drugs shows that they frequently have highly optimised ligand efficiency values for their target. Optimising ligand efficiencies based on both molecular size and lipophilicity, when set in the context of the specific target, has the potential to ameliorate the molecular inflation that pervades current practice in medicinal chemistry, and to increase the developability of drug candidates