Maximum power density for an endoreversible carnot heat engine

An analysis using maximum power-density criteria has been carried out for an endoreversible Carnot heat engine. The results have been compared with known results on maximum power analysis. The design parameters at maximum power density lead to smaller and more efficient endoreversible Carnot heat engines than those working at maximum power output.     

Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

A quantum‐tunneling metal‐insulator‐metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP‐CVD) for the first time. This scalable method is used to produce MIM diodes with high‐quality, pinhole‐free Al₂O₃ films more rapidly than by conventional vacuum‐based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum‐enabled devices. In fact, the MIM diodes fabricated by AP‐CVD show a lower effective barrier height (2.20 eV) at the electrode–insulator interface than those fabricated by conventional plasma‐enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero‐bias resistance, and better asymmetry of 107.     

Characterization of the Hansenula polymorpha CPY gene encoding carboxypeptidase Y

We have isolated the Hansenula polymorpha CPY gene encoding carboxypeptidase Y (Hp-CPY). The deduced amino acid sequence revealed that Hp-CPY consists of 541 amino acids and has a calculated Mr of 60,793. The protein is highly similar to Saccharomyces cerevisiae CPY (61.8% identity). At the N-terminus of Hp-CPY signals for the entry into the secretory pathway and subsequent sorting to the vacuole were identified. Immunocytochemically, using monospecific antibodies raised against Hp-CPY, the protein was localized to the vacuole. On Western blots, a diffuse protein band was observed in extracts of H. polymorpha cells, suggesting that the protein is glycosylated. This was confirmed by endoglycosidase H treatment, which resulted in a strong reduction of the apparent Mr of the protein. We have investigated the effect of CPY deletion on the degradation of peroxisomes, an autophagous process that occurs when the organelles become redundant for growth. In deltacpy cells peroxisomal proteins were degraded in the vacuole as efficiently as in wild-type H. polymorpha cells, indicating that CPY is not a major proteinase in this pathway.     

Penalized-likelihood estimators and noise analysis forrandoms-precorrected PET transmission scans

This paper analyzes and compares image reconstruction methods based on practical approximations to the exact log likelihood of randoms-precorrected positron emission tomography (PET) measurements. The methods apply to both emission and transmission tomography, however, in this paper we focus on transmission tomography. The results of experimental PET transmission scans and variance approximations demonstrate that the shifted Poisson (SP) method avoids the systematic bias of the conventional data-weighted least squares (WLS) method and leads to significantly lower variance than conventional statistical methods based on the log likelihood of the ordinary Poisson (OP) model. We develop covariance approximations to analyze the propagation of noise from attenuation maps into emission images via the attenuation correction factors (ACF's). Empirical pixel and region variances from real transmission data agree closely with the analytical predictions. Both the approximations and the empirical results show that the performance differences between the OP model and SP model are even larger, when considering noise propagation from the transmission images into the final emission images, than the differences in the attenuation maps themselves.     

Assessment of the antioxidant potential and fatty acid composition of four Centaurea L. taxa from Turkey

This paper focused on the assessment of antioxidant property and fatty acid composition of four Centaurea species. The antioxidant activity of its methanol extract was evaluated by several in vitro experiments including phosphomolybedum assay, DPPH assay, β-carotene/linoleic acid, ferric and cupric reducing power. Total phenolic and flavonoid contents were also evaluated. The methanol extract of Centaurea pulcherrima var. pulcherrima showed the superior free radical scavenging activity, linoleic acid inhibition capacity, reducing power and also had the highest total phenolic content. A significant relationship between antioxidant capacity and total phenolic components was found. The oils of Centaurea taxa were also analysed for fatty acid concentration by gas chromatography. The principal fatty acids in the species were palmitic acid (23.38–30.49%) and linoleic acid (20.19–29.93%). These findings suggest that the Centaurea species could be used as a potential source of new natural antioxidants and unsaturated fatty acids in food industry, cosmetics and pharmaceutical preparations.     

A multiplexed separation of iron oxide nanocrystals using variable magnetic fields

The size-dependent magnetic properties of nanocrystals are exploited in a separation process that distinguishes particles based on their diameter. By varying the magnetic field strength, four populations of magnetic materials were isolated from a mixture. This separation is most effective for nanocrystals with diameters between 4 and 16 nm.