Cfd investigation of spacer-filled channels for membrane distillation

The membrane distillation (MD) process for water desalination is affected by temperature polarization, which reduces the driving force and the efficiency of the process. To counteract this phenomenon, spacer-filled channels are used, which enhance mixing and heat transfer but also cause higher pressure drops. Therefore, in the design of MD modules, the choice of the spacer is crucial for process efficiency. In the present work, different overlapped spacers are investigated by computational fluid dynamics (CFD) and results are compared with experiments carried out with thermochromic liquid crystals (TLC). Results are reported for different flow attack angles and for Reynolds numbers (Re) ranging from ~200 to ~800. A good qualitative agreement between simulations and experiments can be observed for the areal distribution of the normalized heat transfer coefficient. Trends of the average heat transfer coefficient are reported as functions of Re for the geometries investigated, thus providing the basis for CFD-based correlations to be used in higher-scale process models

On the full scale and model scale cavitation comparisons of a Deep-V catamaran research vessel

In pushing for greener ships and more sustainable operations, designers and researchers are being challenged to increase vessel performance whilst reducing environmental impact. One topical, and a somewhat challenging aspect of this pursuit, is the reduction in Underwater Radiated Noise (URN). There are several European Collaborative Research Projects currently underway that aim to outline a framework for noise standards, amongst these projects is the Seventh Framework Project (FP7) “Suppression of Underwater Noise Induced by Cavitation” (SONIC) that has been tasked with concentrating on the URN from propeller cavitation; the main contributor to underwater noise generation. As one of the participants of the SONIC project the Newcastle University was involved in the full-scale trials and model-scale propeller testing campaign. The full-scale trial conducted on board Newcastle University’s catamaran research vessel R/V The Princess Royal involved cavitation observations though the dedicated observation windows above each propeller, Propeller Excited Vibration measurements as well as the off-board URN measurements. The model scale tests were made in The Emerson Cavitation Tunnel using a 1:3.5 scale dummy model of the starboard side demi-hull of the vessel. These tests tried to emulate, as best as possible, the full-scale trials in terms of measurement locations and viewing angles

A stereological and histopathological study of the effects of exposure of male rat testes to mercury vapor

Mercury is ubiquitous in the environment; it is an occupational pollutant and a potential toxicant. We investigated the effects of exposure of rat testes to mercury vapor (Hg-0). Twelve male rats were divided into two groups of six: the rats of the Hg-0 group were exposed to mercury (1 mg/m(3)/day) in a chamber for six weeks; the control group rats were housed under the same conditions without exposure to Hg-0. After the experimental period, the testes were removed, sections of testis were evaluated histopathologically after hematoxylin and eosin staining, and stereologically using the Cavalieri principle and optical fractionator methods. We found significant decreases in the total volume of testis, diameters of seminiferous tubules and total volume of seminiferous tubules. Significant decreases were detected in the numbers of Sertoli cells, spermatogonia, spermatocytes and spermatids of the Hg-0 group compared to the control group. In the Hg-0 exposed group, spermatogenic cells were degenerated and seminiferous tubules were atrophied.This study was supported by Ataturk University Scientific Project Fun

Analysis of XACML policies with SMT

The eXtensible Access Control Markup Language (XACML) is an extensible and flexible XML language for the specification of access control policies. However, the richness and flexibility of the language (along with the verbose syntax of XML) come with a price: errors are easy to make and difficult to detect when policies grow in size. If these errors are not detected and rectified, they can result in serious data leakage and/or privacy violations leading to significant legal and financial consequences. To assist policy authors in the analysis of their policies, several policy analysis tools have been proposed based on different underlying formalisms. However, most of these tools either abstract away functions over non-Boolean domains (hence they cannot provide information about them) or produce very large encodings which hinder the performance. In this paper, we present a generic policy analysis framework that employs SMT as the underlying reasoning mechanism. The use of SMT does not only allow more fine-grained analysis of policies but also improves the performance. We demonstrate that a wide range of security properties proposed in the literature can be easily modeled within the framework. A prototype implementation and its evaluation are also provided

Single coronary artery incidence in 215,140 patients undergoing coronary angiography

Background: The aim of our study is to determine the incidence of single coronary artery (SCA). SCA is a rarely seen coronary anomaly in which the right coronary artery and the left main coronary artery arise from single aortic sinus. Although SCA has a benign course in most cases and its clinical significance is unknown, in some autopsy studies it was shown to be related to sudden cardiac death. Materials and methods: SCA patients detected among 215,140 coronary angiographies (CAG) performed between 1998 and 2013 in SANKO Hospital were included in our study. The classification of CAG was made according to the two different classifications defined by Smith and Lipton and colleagues. Results: A total number of 215,140 patients who underwent routine CAG were included in the study, and SCA was detected in 67 (0.031%) patients. There were 6 (9%) type R-I, 23 (34%) type R-II, 10 (15%) type R-III, 16 (24%) type L-I and 12 (18%) type L-II patients according to the angiographic classification. Conclusions: SCA is rarely seen during routine cardiac catheterisation and its incidence is 0.014–0.066% in angiographic series. In our study, the incidence was shown to be similar to the previous studies.

Aneuploidy in pluripotent stem cells and implications for cancerous transformation

Owing to a unique set of attributes, human pluripotent stem cells (hPSCs) have emerged as a promising cell source for regenerative medicine, disease modeling and drug discovery. Assurance of genetic stability over long term maintenance of hPSCs is pivotal in this endeavor, but hPSCs can adapt to life in culture by acquiring non-random genetic changes that render them more robust and easier to grow. In separate studies between 12.5% and 34% of hPSC lines were found to acquire chromosome abnormalities over time, with the incidence increasing with passage number. The predominant genetic changes found in hPSC lines involve changes in chromosome number and structure (particularly of chromosomes 1, 12, 17 and 20), reminiscent of the changes observed in cancer cells. In this review, we summarize current knowledge on the causes and consequences of aneuploidy in hPSCs and highlight the potential links with genetic changes observed in human cancers and early embryos. We point to the need for comprehensive characterization of mechanisms underpinning both the acquisition of chromosomal abnormalities and selection pressures, which allow mutations to persist in hPSC cultures. Elucidation of these mechanisms will help to design culture conditions that minimize the appearance of aneuploid hPSCs. Moreover, aneuploidy in hPSCs may provide a unique platform to analyse the driving forces behind the genome evolution that may eventually lead to cancerous transformation

Identifying rare variant associations in population-based and family-based designs

For almost all complex traits studied in humans, the identified genetic variants discovered to date have accounted for only a small portion of the estimated trait heritability. Consequently, several methods have been developed to identify rare single-nucleotide variants associated with complex traits for population-based designs. Because rare disease variants tend to be enriched in families containing multiple affected individuals, family-based designs can play an important role in the identification of rare causal variants. In this study, we utilize Genetic Analysis Workshop 18 simulated data to examine the performance of some existing rare variant identification methods for unrelated individuals, including our recent method (rPLS). The simulated data is used to investigate whether there is an advantage to using family data compared to case-control data. The results indicate that population-based methods suffer from power loss, especially when the sample size is small. The family-based method employed in this paper results in higher power but fails to control type I error. Our study also highlights the importance of the phenotype choice, which can affect the power of detecting causal genes substantially

A new energy saving twin rudder system - Gate Rudder

Rudder and propeller of a ship share almost similar long service history. The rudder is usually placed behind the propeller to make use of the strong slipstream flow of the propeller. By changing the direction of the slipstream flow the rudder functions as a remarkably effective control surface to maneuver the ship. While this is the fact the rudder also has several disadvantages including: (a) increased ship resistance as an appendage to the hull; (b) modifications to the stern arrangement to accommodate the rudder that enforces restriction not only to the propeller aperture but also to the engine room arrangement; (c) a non-uniform flow imposed in the propeller plane that can easily increase the vibration and noise originated not only from the propeller but also from the combination of the propeller with the rudder; (d) cavitation erosion on the rudder which can be annoying for high speed vessels In order to eliminate the above disadvantages as well as saving further energy, a new concept of twin rudder system is invented one of the Authors and called “Gate Rudder” in which each of the asymmetric rudders is located aside the propeller to exploit the benefits of an accelerating duct device. The main objective of this paper is to give the background for the gate rudder development and present methodology for powering performance of a ship with the gate rudder using the Emerson Cavitation Tunnel facility. The analysis include model tests to measure the local forces on the stern part of a model hull and gate rudder system in the cavitation tunnel as well as the prediction of the gate rudder induced velocities using computational methods. The papers further presents a flow chart for the fine powering performance prediction technology and cost effectiveness analysis of vessels using the gate rudder system