The turbomachine blading design using S2-S1 approach

The boundary conditions corresponding to the design problem when the blades being simulated by the bound vorticity distribution are presented. The 3D flow is analyzed by the two steps S2 - S1 approach. In the first step, the number of blades is supposed to be infinite, the vortex distribution is transformed into an axisymmetric one, so that the flow field can be analyzed in a meridional plane. The thickness distribution of the blade producing the flow channel striction is taken into account by the modification of metric tensor in the continuity equation. Using the meridional stream function to define the flow field, the mass conservation is satisfied automatically. The governing equation is deduced from the relation between the azimuthal component of the vorticity and the meridional velocity. The value of the azimuthal component of the vorticity is provided by the hub to shroud equilibrium condition. This step leads to the determination of the axisymmetric stream sheets as well as the approximate camber surface of the blade. In the second step, the finite number of blades is taken into account, the inverse problem corresponding to the blade to blade flow confined in each stream sheet is analyzed. The momentum equation implies that the free vortex of the absolute velocity must be tangential to the stream sheet. The governing equation for the blade to blade flow stream function is deduced from this condition. At the beginning, the upper and the lower surfaces of the blades are created from the camber surface obtained from the first step with the assigned thickness distribution. The bound vorticity distribution and the penetrating flux conservation applied on the presumed blade surface constitute the boundary conditions of the inverse problem. The detection of this flux leads to the rectification of the geometry of the blades

Determinants of Corporate Disclosure in Financial Statements: Evidence from Vietnamese Listed Firms

Using data of listed firms on Hochiminh Stock Exchange, the study examines determinants of corporate disclosure in financial statements. In line with the literature, the findingsshow that firm size, the use of financial leverage and the presence of supervision board have a positive influence on corporate disclosure. Furthermore, auditing firm (whether a Big4 or not) also plays an important role in the degree of information disclosure by firms.Contradicting to the literature, however state ownership and the proportion of non-executive members in director board show a negative relation to corporate disclosure level. These counter factscanbe explained by real situations of Vietnam over the studied period. Finally, the concurrent role between chair of director board and managing director reduces corporate disclosure degree, as predicted by the agency theory

Infrared spectroscopy of the largest known trans-neptunian object 2001 KX76

We report complete near-infrared (0.9-2.4 $\mu$m) spectral observations of the largest know trans-neptunian objects (TNO) 28976 = 2001 KX$_{76}$ taken in two different nights using the new Near Infrared Camera Spectrometer (NICS) attached to the 3.56m Telescopio Nazionale Galileo (TNG). The spectra are featureless and correspond to a neutral colored object. Our observations indicate that the surface of 2001 KX$_{76}$ is probably highly evolved due to long term irradiation, and that collisional resurfacing processes have not played an important role in its evolution.Comment: 1 Latex file, 2 postscript files. A&A in pres

A review on life cycle environmental impacts of emerging solar cells

The development of solar technologies requires increased efficiency in converting solar radiation to energy, as well as innovative materials and structure to go beyond the conventional power conversion ratio. In line with these innovations, there are concerns about greenhouse gas emissions of the solar cells, materials for the solar technologies and other relevant environmental impacts of the manufacturing processes. This review is conducted on life cycle assessments of solar cells, considering the climate change and natural resource shortage context. It is identified that the majority of existing life cycle assessments on solar cells take into account four typical environmental impacts: energy consumption, greenhouse gas emissions, material depletion, and toxicity. Though the diverse methodological aspects make it difficult to directly compare these environmental impacts among various types of solar cells, the obtained results hinder that emerging solar cells such as perovskite solar cells or tandem solar cells are likely to have better environmental profiles than conventional silicon based and thin film solar cells, in terms of energy consumption, greenhouse gas emissions and material consumption. However, the emerging solar cells may utilize toxic materials in which their eco-toxicity and human toxicity should be further considered during the design of the technologies. Moreover, it is identified that the energy and environmental hotspot lies in the manufacturing process, regardless of impact indicators and types of solar cells

A Comparison of the Life-Cycle Impacts of the Concentrating Solar Power with the Product Environmental Footprint and ReCiPe Methods

Concentrating solar power (CSP) technologies have the potential to reduce the carbon emissions in the economy and energy sector. The growing significance of solar energy sources in addressing climate change highlights the necessity for thorough assessments of their environmental impacts. This paper explores two different life-cycle impact assessment methods, ReCiPe and Product Environmental Footprint, using CSP plants with various receiver systems and heat-transfer fluids as a case study. In terms of the overall life-cycle impact, solar towers are shown to have advantages over parabolic troughs. Most of the life-cycle impacts of solar towers are lower than those of parabolic troughs, ranging from 8% to 112%, except for human toxicity and land use impacts. However, there is not much difference between the studied heat-transfer fluids, with the variance of most impacts being less than around 1%. The single-score results indicates that the ReCiPe method assigns significance to human health impacts, while the product environmental footprint method gives equal attention to all aspects. Meanwhile the comparison of components’ contributions quantified by the two methods shows the same results for more than half of the impact categories

Development and comparison of novel multiple cross displacement amplification (MCDA) assays with other nucleic acid amplification methods for SARS-CoV-2 detection

The development of alternative isothermal amplification assays including multiple cross displacement amplification (MCDA) may address speed and portability limitations of real-time PCR (rt-PCR) methods for SARS-CoV-2 detection. We developed a novel SARS-CoV-2 MCDA assay and compared its speed and sensitivity to loop-mediated isothermal amplification (LAMP) and rt-PCR. Two MCDA assays targeting SARS-CoV-2 N gene and ORF1ab were designed. The fastest time to detection and sensitivity of MCDA was compared to LAMP and rt-PCR using DNA standards and transcribed RNA. For the N gene, MCDA was faster than LAMP and rt-PCR by 10 and 20 min, respectively with fastest time to detection at 5.2 min. rt-PCR had the highest sensitivity with the limit of detection at 10 copies/µl compared with MCDA (100 copies/µl) and LAMP (500 copies/µl). For ORF1ab, MCDA and LAMP had similar speed with fastest time to detection at 9.7 and 8.4 min, respectively. LAMP was more sensitive for ORF1ab detection with 50 copies/µl compared to MCDA (500 copies/µl). In conclusion, different nucleic acid amplification methods provide different advantages. MCDA is the fastest nucleic acid amplification method for SARS-CoV-2 while rt-PCR is the most sensitive. These advantages should be considered when determining the most suitable nucleic acid amplification methods for different applications

Comparative Phosphoproteomics of Classical Bordetellae Elucidates the Potential Role of Serine, Threonine and Tyrosine Phosphorylation in Bordetella Biology and Virulence.

The Bordetella genus is divided into two groups: classical and non-classical. Bordetella pertussis, Bordetella bronchiseptica and Bordetella parapertussis are known as classical bordetellae, a group of important human pathogens causing whooping cough or whooping cough-like disease and hypothesized to have evolved from environmental non-classical bordetellae. Bordetella infections have increased globally driving the need to better understand these pathogens for the development of new treatments and vaccines. One unexplored component in Bordetella is the role of serine, threonine and tyrosine phosphorylation. Therefore, this study characterized the phosphoproteome of classical bordetellae and examined its potential role in Bordetella biology and virulence. Applying strict identification of localization criteria, this study identified 70 unique phosphorylated proteins in the classical bordetellae group with a high degree of conservation. Phosphorylation was a key regulator of Bordetella metabolism with proteins involved in gluconeogenesis, TCA cycle, amino acid and nucleotide synthesis significantly enriched. Three key virulence pathways were also phosphorylated including type III secretion system, alcaligin synthesis and the BvgAS master transcriptional regulatory system for virulence genes in Bordetella. Seven new phosphosites were identified in BvgA with 6 located in the DNA binding domain. Of the 7, 4 were not present in non-classical bordetellae. This suggests that serine/threonine phosphorylation may play an important role in stabilizing/destabilizing BvgA binding to DNA for fine-tuning of virulence gene expression and that BvgA phosphorylation may be an important factor separating classical from non-classical bordetellae. This study provides the first insight into the phosphoproteome of classical Bordetella species and the role that Ser/Thr/Tyr phosphorylation may play in Bordetella biology and virulence