A Review: Durability of Fired Clay Brick Masonry Wall due to Salt Attack

This paper offers a review on durability of fired clay brick masonry wall due to salt attack. Durability of brick normally affected when an external masonry walls are exposed to aggressive environment. Masonry structures, when subjected to salt attack or exposed to aggressive environment during their service life may suffer degradation due to the formation of crystallization pressure as a result of the evaporation of soluble salt in clay masonry structures. The crystallization pressures produce normally higher than tensile stress of clay brick and sufficient to damage the masonry structures. The mechanism of salt attack must be prevented and addressed thoroughly in order to maintain the integrity and service life of masonry wall. Therefore, the summary of durability, factors, mechanism and main sources of salt attack on fired clay brick masonry walls are discussed

Effect of cutting parameters on surface roughness in dry drilling of AISI D2 tool steel by using Taguchi Method

Hard drilling of AISI D2 reportedly produce accelerated wear to the cutting tool that detrimental to the surface finish. This paper presents the effect of drilling tool and drilling parameters by using Taguchi method to produce minimum surface roughness under dry conditions. The experiments were conducted using high speed steel (HSS) based drilling tools, coated with various coating layer (uncoated, TiN and TiCN) on material AISI D2 tool steel. Two cutting parameters, spindle speed and feed rate, each at three levels were considered. An L9 array, the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) were employed to analyze the significant and percentage of each parameters for minimum surface roughness. The results revealed that the drilling tools gave main affects the surface roughness based on the highest percentage distribution (95%), followed by the spindle speed (3%) and feed rate (0.4%). Further, the results of ANOVA indicated that the combination of optimum parameter recorded as drilling tools HSS-TiCN with spindle speed of 680 rpm and feed rate of 206.25 mm/min

L-band R-EDFA/Raman hybrid amplifier with enhanced higher-order pumping scheme utilizing stimulated Raman scattering.

An enhanced pump delivery scheme for L-band remote erbium-doped fiber/Raman (R-EDFA/Raman) hybrid amplifier utilizing stimulated Raman scattering (SRS) is demonstrated. The technique benefits from the use of higher-order pumps that are realized by generating C-band SRS and ultra-long Raman fiber laser (ULRFL). A section of passive erbium-doped fiber is deployed at the end of the transmission span to exploit the ULRFL pump for additional amplification. Gain clamping effect is observed at the R-EDFA and passive EDF due to saturation from the higher-order pumps. Tuning the pump wavelengths to a region away from the amplification bandwidth could remove the gain-clamping effect and produce maximum gain performance

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

CFD Analysis of Flow, Pollutant Dispersion and Thermal Effects in Street Canyons

Aim of this study is to investigate the pollutant dispersion inside an urban street canyon so that the understanding of the characteristics of air flow subjected to the dispersion of pollutant can help achieve greater air quality urban areas, sustainably for improving the health and comfort of the people. Using numerical method through Computational Fluid Dynamic Software ANSYS Fluent, a simplified two dimensional street canyon is modeled to simulate the flow of pollutant subjected to building geometry as well as wind speed. The building height and street width were manipulated throughout the study. A series of multiphase analysis were conducted with different building height to street width ratio to examine the pollutant dispersion rate. With the volume fraction gradually decrease from Φ=1 to a certain value that indicates the pollutant has disperse. The result presented the relation between the street canyon geometry and the pollutant dispersion rate, with wider streets proves to have a better pollution dispersion rate as well as when the wind speed is higher. The significant of the study is to see effect of the street canyon geometry to the rate of pollutant dispersion

Effect of Cutting Parameters on Surface Roughness in Dry Drilling of AISI D2 Tool Steel by Using Taguchi Method

Hard drilling of AISI D2 reportedly produce accelerated wear to the cutting tool that detrimental to the surface finish. This paper presents the effect of drilling tool and drilling parameters by using Taguchi method to produce minimum surface roughness under dry conditions. The experiments were conducted using high speed steel (HSS) based drilling tools, coated with various coating layer (uncoated, TiN and TiCN) on material AISI D2 tool steel. Two cutting parameters, spindle speed and feed rate, each at three levels were considered. An L9 array, the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) were employed to analyze the significant and percentage of each parameters for minimum surface roughness. The results revealed that the drilling tools gave main affects the surface roughness based on the highest percentage distribution (95%), followed by the spindle speed (3%) and feed rate (0.4%). Further, the results of ANOVA indicated that the combination of optimum parameter recorded as drilling tools HSS-TiCN with spindle speed of 680 rpm and feed rate of 206.25 mm/min

The clinical and environmental spread and diversity of toxigenic Clostridium difficile diarrhea in the region of the Middle East.

Stool samples of 1822 hospitalized patients with nosocomial diarrhea and 100 environmental samples were collected at three teaching hospitals and PCR amplification of rRNA intergenic spacer regions (ISR) was conducted. Bacterial cytotoxicity was assayed by conducting three assays namely toxigenic culture on vero cells, stool cytotoxin, and enzyme immunoassay. ISR was carried out using two universal primers complementary to conserved regions in the 16S and 23S rRNA genes. It was found that the toxigenic culture, stool cytotoxin and enzyme immunoassay showed close rates of detection of toxigenic C. difficile, 124, 121, and 122 /1822 (6.8, 6.64., and 6.7%) respectively. In addition, 32 different ribotypes for toxigenic C. difficile were detected, 28 in clinical and 6 in environmental isolates. The predominant ribotypes from the clinical isolates were 13-15, 35.6%, of isolates. Ribotypes were associated with age, location of isolation, and severity of symptoms of clostridial diarrhea (P<0.05). Ribotypes 6-9 affected children only. The most common ribotype of C. difficile , no. 13, as well as ribotypes 16, 20, and 4 covered almost the whole range of severity of symptoms. Ribotypes 21-27, 1, 3, 6, 7, 9, 11, 14, and 19 caused mild-moderate CDAD symptoms while ribotypes 5, 10 8, 12, 15, 17, and 28 were dominantly of severe symptoms (P<0.05). Environmental isolates showed 17% toxigenic strains composed of 4 different ribotypes while ribotypes 5 was shared with clinical isolates. These findings showed that C. difficile associated with diarrhea were genetically diverse and linked to environmental strains

Mathematical prediction of the compressive strength of bacterial concrete using gene expression programming

The impact of microbial calcium carbonate on concrete strength has been extensively evaluated in the literature. However, there is no predicted equation for the compressive strength of concrete incorporating ureolytic bacteria. Therefore, in the present study, 69 experimental tests were taken into account to introduce a new predicted mathematical formula for compressive strength of bacterial concrete with different concentrations of calcium nitrate tetrahydrate, urea, yeast extract, bacterial cells and time using Gene Expression Programming (GEP) modelling. Based on the results, statistical indicators (MAE, RAE, RMSE, RRSE, R and R2) proved the capability of the GEP 2 model to predict compressive strength in which minimum error and high correlation were achieved. Moreover, both predicted and actual results indicated that compressive strength decreased with the increase in nutrient concentration. In contrast, the compressive strength increased with increased bacterial cells concentration. It could be concluded that GEP2 were found to be reliable and accurate compared to that of the experimental results

Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber.

A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm

Amelioration of mitochondrial dysfunction-induced insulin resistance in differentiated 3T3-L1 adipocytes via inhibition of NF-kappa B pathways

A growing body of evidence suggests that activation of nuclear factor kappa B (NF-kappa B) signaling pathways is among the inflammatory mechanism involved in the development of insulin resistance and chronic low-grade inflammation in adipose tissues derived from obese animal and human subjects. Nevertheless, little is known about the roles of NF-kappa B pathways in regulating mitochondrial function of the adipose tissues. In the present study, we sought to investigate the direct effects of celastrol (potent NF-kappa B inhibitor) upon mitochondrial dysfunction-induced insulin resistance in 3T3-L1 adipocytes. Celastrol ameliorates mitochondrial dysfunction by altering mitochondrial fusion and fission in adipocytes. The levels of oxidative DNA damage, protein carbonylation and lipid peroxidation were down-regulated. Further, the morphology and quantification of intracellular lipid droplets revealed the decrease of intracellular lipid accumulation with reduced lipolysis. Moreover, massive production of the pro-inflammatory mediators tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) were markedly depleted. Insulin-stimulated glucose uptake activity was restored with the enhancement of insulin signaling pathways. This study signified that the treatments modulated towards knockdown of NF-kappa B transcription factor may counteract these metabolic insults exacerbated in our model of synergy between mitochondrial dysfunction and inflammation. These results demonstrate for the first time that NF-kappa B inhibition modulates mitochondrial dysfunction induced insulin resistance in 3T3-L1 adipocytes