Boron Fullerenes: A First-Principles Study

A family of unusually stable boron cages was identified and examined using first-principles local density functional method. The structure of the fullerenes is similar to that of the B12 icosahedron and consists of six crossing double-rings. The energetically most stable fullerene is made up of 180 boron atoms. A connection between the fullerene family and its precursors, boron sheets, is made. We show that the most stable boron sheets are not necessarily precursors of very stable boron cages. Our finding is a step forward in the understanding of the structure of the recently produced boron nanotubes.Comment: 10 pages, 4 figures, 1 tabl

Laminated Jute and Glass Fibre Reinforced Composite for Repairing Concrete Through Wrapping Technique

In the recent decades, the research of natural fibre in concrete structure materials had attracted many researchers and engineers due to its good agreement in mechanical properties, economically and sustainability. In this study, the jute and glass fibre laminated composite for repairing concrete through the wrapping technique was analysed. A total of 66 concrete specimens, 150 x 50 mm each, were tested. Six concrete specimens were kept as control specimen, 30 specimens were laminated with glass fibre-reinforced thermoset (GFRT) and 30 specimens were laminated with jute fibre-reinforced thermoset (JFRT). The vinyl ester (VE) was used as a matrix. Eventually, all specimen was tested using compression and Brazilian testing. It was found that both GFRT and JFRT had the potential to improve the mechanical performance of concrete specimens with the increment of a maximum number of five (5) layers of woven fibre. It was also found that the four (4) layers of JFRT had the highest mechanical properties with improvement of 72.62% compare to GFRT (4 layers). The results presented here may facilitate improvements in the concrete specimen by using JFRT where it had been suggested to have a higher improvement for the concrete specimen with the optimum layers applied. Hence, jute fibre had been proven to have better performance and can replace the use of glass fibre

Laminated Jute and Glass Fibre Reinforced Composite for Repairing Concrete Through Wrapping Technique

In the recent decades, the research of natural fibre in concrete structure materials had attracted many researchers and engineers due to its good agreement in mechanical properties, economically and sustainability. In this study, the jute and glass fibre laminated composite for repairing concrete through the wrapping technique was analysed. A total of 66 concrete specimens, 150 x 50 mm each, were tested. Six concrete specimens were kept as control specimen, 30 specimens were laminated with glass fibre-reinforced thermoset (GFRT) and 30 specimens were laminated with jute fibre-reinforced thermoset (JFRT). The vinyl ester (VE) was used as a matrix. Eventually, all specimen was tested using compression and Brazilian testing. It was found that both GFRT and JFRT had the potential to improve the mechanical performance of concrete specimens with the increment of a maximum number of five (5) layers of woven fibre. It was also found that the four (4) layers of JFRT had the highest mechanical properties with improvement of 72.62% compare to GFRT (4 layers). The results presented here may facilitate improvements in the concrete specimen by using JFRT where it had been suggested to have a higher improvement for the concrete specimen with the optimum layers applied. Hence, jute fibre had been proven to have better performance and can replace the use of glass fibre

Low threshold linear cavity mode-locked fiber laser using microfiber-based carbon nanotube saturable absorber

In this work, we demonstrate a linear cavity mode-locked erbium-doped fiber laser in C-band wavelength region. The passive mode-locking is achieved using a microfiber-based carbon nanotube saturable absorber. The carbon nanotube saturable absorber has low saturation fluence of 0.98 µJ/cm2. Together with the linear cavity architecture, the fiber laser starts to produce soliton pulses at low pump power of 22.6 mW. The proposed fiber laser generates fundamental soliton pulses with a center wavelength, pulse width, and repetition rate of 1557.1 nm, 820 fs, and 5.41 MHz, respectively. This mode-locked laser scheme presents a viable option in the development of low threshold ultrashort pulse system for deployment as a seed laser

An adaptive inelastic magnetic mirror for Bose-Einstein condensates

We report the reflection and focussing of a Bose-Einstein condensate by a new pulsed magnetic mirror. The mirror is adaptive, inelastic, and of extremely high optical quality. The deviations from specularity are less than 0.5 mrad rms, making this the best atomic mirror demonstrated to date. We have also used the mirror to realize the analog of a beam-expander, producing an ultra-cold collimated fountain of matter wavesComment: 4 pages, 4 figure

Acute Haemodynamic Changes During Haemodialysis Do Not Exacerbate Gut Hyperpermeability

© 2019 The Author(s)Introduction: The gastrointestinal tract is a potential source of inflammation in dialysis patients. In-vitro studies suggest breakdown of the gut barrier in uraemia leading to increased intestinal permeability and it is hypothesised that haemodialysis exacerbates this problem due to mesenteric ischemia induced by blood volume changes during treatment. Method: The effect of haemodialysis on intestinal permeability was studied in ten haemodialysis patients and compared with five controls. Intestinal permeability was assessed by measuring the differential absorption of four orally administered sugar probes which provides an index of small and whole bowel permeability. A multi-sugar solution (containing lactulose, rhamnose, sucralose and erythritol) was orally administered after an overnight fast. Plasma levels of all sugar probes were measured hourly for 10hrs post-administration. In haemodialysis patients, the procedure was carried out twice – once on a non-dialysis day and once immediately after haemodialysis. Results: Area under curve (AUC) for lactulose: rhamnose (L:R) ratio and sucralose: erythritol (S:E) ratio was similar post-dialysis and on non-dialysis days. AUC for L:R was higher in haemodialysis patients compared to controls (0.071 vs. 0.034,p=0.001), AUC for S:E ratio was not significantly different. Levels of lactulose, sucralose and erythritol were elevated and retained for longer in haemodialysis patients compared to controls due to dependence of sugars on kidney function for clearance. Conclusion: We found no significant acute changes in intestinal permeability in relation to the haemodialysis procedure. Valid comparison of intestinal permeability between controls and haemodialysis patients was not possible due to the strong influence of kidney function on sugar levels.Peer reviewedFinal Published versio

The role of point-like topological excitations at criticality: from vortices to global monopoles

We determine the detailed thermodynamic behavior of vortices in the O(2) scalar model in 2D and of global monopoles in the O(3) model in 3D. We construct new numerical techniques, based on cluster decomposition algorithms, to analyze the point defect configurations. We find that these criteria produce results for the Kosterlitz-Thouless temperature in agreement with a topological transition between a polarizable insulator and a conductor, at which free topological charges appear in the system. For global monopoles we find no pair unbinding transition. Instead a transition to a dense state where pairs are no longer distinguishable occurs at T<Tc, without leading to long range disorder. We produce both extensive numerical evidence of this behavior as well as a semi-analytic treatment of the partition function for defects. General expectations for N=D>3 are drawn, based on the observed behavior.Comment: 14 pages, REVTEX, 13 eps figure

The state-of-the-art development of photocatalysts for degrading of persistent herbicides in aqueous environment

Herbicides are one of the most recurring pollutants in the aquatic system due to their widespread usage in the agriculture sector for weed control. Semiconductor-based photocatalysts have gained recognition due to their ability to degrade and mineralize pollutants into harmless by-products completely. Lately, many studies have been done to design photocatalysts with efficient separation of photogenerated charge carriers and enhanced light absorption. Photocatalyst engineering through doping with metal and non-metal elements and the formation of heterojunction are proven effective for minimizing the recombination of electron-hole pairs and enlarging the absorption in the visible light region. This review focuses on discussing and evaluating the recent progress in the types of photocatalysts and their performance in the remediation of herbicides in wastewater. The development of innovative hybrid technologies is also highlighted. The limitations and challenges of photocatalysis technology in the present literature have been identified, and future studies are recommended

A possible rheological model of gum candies

An appropriate rheological model can be used in production of good quality gum candy required by consumers. For this purpose Creep-Recovery Test (CRT) curves were recorded with a Stable Micro System TA.XT-2 precision texture analyser with 75 mm diameter cylinder probe on gum candies purchased from the local market. The deformation speed was 0.2 mm s−1, the creeping- and recovering time was 60 s, while the loading force was set to 1 N, 2 N, 5 N, 7 N, and 10 N. The two-element Kelvin-Voigt-model, a three-element model, and the four-element Burgers-model were fitted on the recorded creep data, and then the parameters of the models were evaluated. The best fitting from the used models was given by the Burgers model