Highly selective fluoride sensing via chromogenic aggregation of a silyloxy-functionalized tetraphenylethylene (TPE) derivative

Cataloged from PDF version of article.A silyloxy-functionalized tetraphenylethylene (TPE) derivative shows a remarkable change in the absorption spectrum on deprotection with fluoride ions. The reaction process is highly selective for fluoride and the resulting charge transfer band results in a bright green solution. A simple selective visual assay of aqueous fluoride ions was also obtained by the impregnation of cellulose strips with the TPE derivative

Low strain rate mechanical performance of balsa wood and carbon fibre-epoxy-balsa sandwich structures

The focus of this study is the experimental assessment of the mechanical behaviour of balsa wood and its sandwich structures, where balsa serves as the core, supported by carbon fibre-epoxy skin layers. A comprehensive characterisation is conducted on the mechanical behaviour of balsa wood and carbon fibre-epoxy balsa core sandwich structures subjected to a range of low strain rates. Initially, the study undertakes a consistent procedure for sample preparation. Subsequently, the characterisation of the manufactured composite structures is performed experimentally. A stereo microscope is employed for a detailed visual inspection of the internal structure of the balsa wood and the sandwich structures. Furthermore, the mechanical characterisation is carried out with three-point bending tests at a range of strain rates from 0.1 % to 6 % strain per minute. This research reveals key findings about balsa wood and its sandwich structures, highlighting their performance and their sensitivity even under low strain rates

Nutrient control of eukaryote cell growth: a systems biology study in yeast

<p>Abstract</p> <p>Background</p> <p>To elucidate the biological processes affected by changes in growth rate and nutrient availability, we have performed a comprehensive analysis of the transcriptome, proteome and metabolome responses of chemostat cultures of the yeast, <it>Saccharomyces cerevisiae</it>, growing at a range of growth rates and in four different nutrient-limiting conditions.</p> <p>Results</p> <p>We find significant changes in expression for many genes in each of the four nutrient-limited conditions tested. We also observe several processes that respond differently to changes in growth rate and are specific to each nutrient-limiting condition. These include carbohydrate storage, mitochondrial function, ribosome synthesis, and phosphate transport. Integrating transcriptome data with proteome measurements allows us to identify previously unrecognized examples of post-transcriptional regulation in response to both nutrient and growth-rate signals.</p> <p>Conclusions</p> <p>Our results emphasize the unique properties of carbon metabolism and the carbon substrate, the limitation of which induces significant changes in gene regulation at the transcriptional and post-transcriptional level, as well as altering how many genes respond to growth rate. By comparison, the responses to growth limitation by other nutrients involve a smaller set of genes that participate in specific pathways.</p> <p>See associated commentary <url>http://www.biomedcentral.com/1741-7007/8/62</url></p

Nonlinear behaviour of epoxy and epoxy-based nanocomposites: an integrated experimental and computational analysis

The focus of this study is on the nonlinear mechanical properties of epoxy and epoxy-based nanocomposites, exploring frequency and strain amplitude dependency. Nanocomposite samples of epoxy are reinforced with fumed silica (FS), halloysite nanotubes (HNT) and Albipox 1000 rubber (Evonik) nanoparticles. Considering these particles have different geometries and stiffnesses, they are expected to have significantly different influences on the mechanics of the resulting composite. To enhance the reliability of the results and to reveal the impact of nanofillers on the mechanics of the material more distinctly, the manufacturing process is designed to be the same for all the specimens within the same material groups to eliminate the effects of the manufacturing process. The comprehensive characterization process consists of Fourier-Transform InfraRed Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Dynamic Mechanical Analysis (DMA). The DMA tests are designed so that the material properties are measured depending on the vibration frequency and strain amplitude. Finally, the characterized nonlinear dynamic properties of these nanocomposites are used as the input material properties into a numerical model. In this simulation, a cantilever beam with representative nonlinear material properties, for these nanocomposites, is created, as example and its forced response is plotted under the same levels of excitation in the frequency domain. Key effects of the different nanofillers are identified using the resonance behavior, primarily focusing on the stiffness and damping of the epoxy-based nanocomposites. These experimental and numerical procedures followed show the significant impact of the nanoparticle reinforcements on the nonlinear nature of these epoxy-based composites

Characterisation and mechanical modelling of polyacrylonitrile-based nanocomposite membranes reinforced with silica nanoparticles

In this study, neat polyacrylonitrile (PAN) and fumed silica (FS)-doped PAN membranes (0.1, 0.5 and 1 wt% doped PAN/FS) are prepared using the phase inversion method and are characterised extensively. According to the Fourier Transform Infrared (FTIR) spectroscopy analysis, the addition of FS to the neat PAN membrane and the added amount changed the stresses in the membrane structure. The Scanning Electron Microscope (SEM) results show that the addition of FS increased the porosity of the membrane. The water content of all fabricated membranes varied between 50% and 88.8%, their porosity ranged between 62.1% and 90%, and the average pore size ranged between 20.1 and 21.8 nm. While the neat PAN membrane’s pure water flux is 299.8 L/m2 h, it increased by 26% with the addition of 0.5 wt% FS. Furthermore, thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques are used to investigate the membranes’ thermal properties. Finally, the mechanical characterisation of manufactured membranes is performed experimentally with tensile testing under dry and wet conditions. To be able to provide further explanation to the explored mechanics of the membranes, numerical methods, namely the finite element method and Mori–Tanaka mean-field homogenisation are performed. The mechanical characterisation results show that FS reinforcement increases the membrane rigidity and wet membranes exhibit more compliant behaviour compared to dry membranes

Halloysite nanotube-enhanced polyacrylonitrile ultrafiltration membranes: fabrication, characterization, and performance evaluation

This research focuses on the production and characterization of pristine polyacrylonitrile (PAN) as well as halloysite nanotube (HNT)-doped PAN ultrafiltration (UF) membranes via the phase inversion technique. Membranes containing 0.1, 0.5, and 1% wt HNT in 16% wt PAN are fabricated, and their chemical compositions are examined using Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) is utilized to characterize the membranes’ surface and cross-sectional morphologies. Atomic force microscopy (AFM) is employed to assess the roughness of the PAN/HNT membrane. Thermal characterization is conducted using thermal gravimetric analysis (TGA) and differential thermal analysis (DTA), while contact angle and water content measurements reveal the hydrophilic/hydrophobic properties. The pure water flux (PWF) performance of the porous UF water filtration membranes is evaluated at 3 bar, with porosity and mean pore size calculations. The iron (Fe), manganese (Mn), and total organic carbon (TOC) removal efficiencies of PAN/HNT membranes from dam water are examined, and the surfaces of fouled membranes are investigated by using SEM post-treatment. Mechanical characterization encompasses tensile testing, the Mori–Tanaka homogenization approach, and finite element analysis. The findings offer valuable insights into the impact of HNT doping on PAN membrane characteristics and performance, which will inform future membrane development initiatives

Koyunlarda subklinik mastitis: Etiyoloji, epidemiyoloji ve tani yöntemleri

The incidence of mastitis is less frequent in sheep compared to dairy cows. However, there has been a growing interest in sheep mastitis due to a high morbidity rate in acute and peracute forms. Furthermore, sheep with sub-clinical mastitis may develop clinical form of mastitis in poor husbandary condition. Mastitis in sheep is seen in two forms: clinical and subclinical. The clinical form, which has peracute, acute and chronic subforms, is characterized by grossly visible pathological changes in mammary gland and milk. However, the subclinical form bears more importance as the case is often missed due to absence of such changes. Numerous studies on etiology, epidemiology and diagnosis of sheep mastitis indicated that the sheep mastitis resembles to cow mastitis. However, there are important differences between sheep and cow mastitis. This review discusses etiology, epidemiology and current diagnostic techniques in subclinical mastitis in sheep with emphasis on recent updates