The calcium-free form of atorvastatin inhibits amyloid-β(1–42) aggregation in vitro

Alzheimer's disease is characterized by the presence of extraneuronal amyloid plaques composed of amyloid-beta (A beta) fibrillar aggregates in the brains of patients. In mouse models, it has previously been shown that atorvastatin (Ator), a cholesterol-lowering drug, has some reducing effect on the production of cerebral A beta. A meta-analysis on humans showed moderate effects in the short term but no improvement in the Alzheimer's Disease Assessment Scale-Cognitive Subscale behavioral test. Here, we explore a potential direct effect of Ator on A beta 42 aggregation. Using NMR-based monomer consumption assays and CD spectroscopy, we observed a promoting effect of Ator in its original form (Ator-calcium) on A beta 42 aggregation, as expected because of the presence of calcium ions. The effect was reversed when applying a CaCO3- based calcium ion scavenging method, which was validated by the aforementioned methods as well as thioflavin-T fluorescence assays and transmission electron microscopy. We found that the aggregation was inhibited significantly when the concentration of calcium-free Ator exceeded that of A beta by at least a factor of 2. The H-1-N-15 heteronuclear single quantum correlation and saturation-transfer difference NMR data suggest that calcium-free Ator exerts its effect through interaction with the (KLVF19)-K-16 binding site on the A beta peptide via its aromatic rings as well as hydroxyl and methyl groups. On the other hand, molecular dynamics simulations confirmed that the increasing concentration of Ator is necessary for the inhibition of the conformational transition of A beta from an alpha-helix-dominant to a beta-sheet-dominant structure

Investigation the integration of heliostat solar receiver to gas and combined cycles by energy, exergy, and economic point of views

Due to the high amount of natural gas resources in Iran, the gas cycle as one of the main important power production system is used to produce electricity. The gas cycle has some disadvantages such as power consumption of air compressors, which is a major part of gas turbine electrical production and a considerable reduction in electrical power production by increasing the environment temperature due to a reduction in air density and constant volumetric airflow through a gas cycle. To overcome these weaknesses, several methods are applied such as cooling the inlet air of the system by different methods and integration heat recovery steam generator (HRSG) with the gas cycle. In this paper, using a heliostat solar receiver (HSR) in gas and combined cycles are investigated by energy, exergy, and economic analyses in Tehran city. The heliostat solar receiver is used to heat the pressurized exhaust air from the air compressor in gas and combined cycles. The key parameter of the three mentioned analyses was calculated and compared by writing computer code in MATLAB software. Results showed the use of HSR in gas and combined cycles increase the annual average energy efficiency from 28.4% and 48.5% to 44% and 76.5%, respectively. Additionally, for exergy efficiency, these increases are from 29.2% and 49.8% to 45.2% and 78.5%, respectively. However, from an economic point of view, adding the HRSG increases the payback period (PP) and it decreases the net present value (NPV) and internal rate of return (IRR)

The indirect effect of strategic management accounting in the relationship between CEO characteristics and their networking activities, and company performance

Purpose - The purpose of this paper is to investigate the effect of chief executive officer (CEO) characteristics and involvement in networks on strategic management accounting (SMA) and, in turn, the indirect effect of SMA on company performance. Design/methodology/approach - A model is advanced and tested using partial least-squares path modelling and data were collected from a sample of 121 service small and medium-sized enterprises (SMEs) in Malaysia. Findings - The results indicate significant and positive relationships between the CEO education and the application of SMA as well as between involvement in networks and SMA. Moreover, it is found that SMA has an indirect effect in relations of CEO education, involvement in networks and company performance. Practical implications - SMEs' leaders may realize their important role in affecting outcomes by their choices, which are in turn affected by their characteristics and activities. Originality/value - This study provides an empirical evidence on the impact of two new factors on the SMA by considering contingency theory and upper echelons theory simultaneously for explaining relationships and developing a new model

Multi-parametric Improvements in the CCD Camera-based EPID for Portal Dosimetry

Dosimetric verification of radiation treatment has recently been extended by the introduction of electronic portal imaging devices (EPIDs). Detailed dose response specifications of EPID should be addressed prior to any dosimetric application. The present study evaluates improvements of dosimetric properties of the low elbow camera-based EPID Theraview (Cablon Medical, Leusden, The Netherlands) equipped with a cooled charge coupled device (CCD) for portal dosimetry. The dose response, warm-up behavior, stability over long- and short-term scales (throughout a day) were studied. The field size dependency of the EPID response was also investigated and compared with ion chamber measurements under the same conditions. The EPID response without saturation for doses up to 2 Gy was linear for both beam qualities (6 and 15 MV). There was no evident warm-up characteristic. The detector sensitivity showed excellent stability in short term [standard deviation (SD) 0.38%]. In long-term stability (over a period of approximately 3 months), a negligible linear decline of 0.01% per day was observed. It was concluded that the cooled CCD camera-based EPID could be used for portal dosimetry, after accurate corrections for the field size dependency and sensitivity loss

Hull girder ultimate strength assessment according to rules requirements

Residual ultimate strength of hull girder is rather important in naval vessel design, being a fundamental driver and a specific project requirement. In this paper, an applicable approach facing such challenge in pre-liminary naval vessel design is presented in the form of a benchmark study. Two typical case-studies were defined and three damaged positions along the hull length were analysed at different transverse section heights as required by class rules. First case aims at comparing notation requirements provided by Lloyd’s Register and RINA Naval Ship Rules using the same input threat. Second application focuses on results ob-tained by different class support software using damage extent and load conditions defined by Lloyd’s Regis-ter Rules as a baseline. Results of residual ultimate strength analysis of damaged hull girder in all considered cases are outlined and compared, also including results of direct, residual strength, elastoplastic analyses performed by finite element software