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Evaluating the efficiency of nano-sized Cu doped TiO2/ZnO photocatalyst under visible light irradiation
No full textA visible light responsive photocatalyst, nano-sized copper doped TiO2/ZnO, was synthesized by sol gel method. It was characterized in terms of thermal stability, crystalline phase, crystal size, morphology, surface area, UV–Vis DRS and band gap. The results showed that the synergistic effect of copper ions considerably narrowed the band gap of the synthesized photocatalyst compared to TiO2/ZnO. Its photoactivity was then evaluated by measuring degradation efficiency of methyl orange (MO) and methylene blue (MB) in terms of colour, COD and TOC removal. The synergistic or antagonistic effects of different combinations of dye and catalyst concentrations, pH, intensity of light irradiation and reaction time on photoactivity of Cu-TiO2/ZnO were also investigated. The highest photoactivity achieved was 85.45% of colour, 70.56% of COD and 48.70% of TOC removal for MO and 73.20% of colour, 59.92% of COD and 38.77% of TOC removal for MB under optimal conditions
SLAMM: Visual monocular SLAM with continuous mapping using multiple maps
No full textThis paper presents the concept of Simultaneous Localization and Multi-Mapping (SLAMM). It is a system that ensures continuous mapping and information preservation despite failures in tracking due to corrupted frames or sensor’s malfunction; making it suitable for real-world applications. It works with single or multiple robots. In a single robot scenario the algorithm generates a new map at the time of tracking failure, and later it merges maps at the event of loop closure. Similarly, maps generated from multiple robots are merged without prior knowledge of their relative poses; which makes this algorithm flexible. The system works in real time at frame-rate speed. The proposed approach was tested on the KITTI and TUM RGB-D public datasets and it showed superior results compared to the state-of-the-arts in calibrated visual monocular keyframe-based SLAM. The mean tracking time is around 22 milliseconds. The initialization is twice as fast as it is in ORB-SLAM, and the retrieved map can reach up to 90 percent more in terms of information preservation depending on tracking loss and loop closure events. For the benefit of the community, the source code along with a framework to be run with Bebop drone are made available at https://github.com/hdaoud/ORBSLAMM
Comparative study on the performance of the MQL nanolubricant and conventional flood lubrication techniques during grinding of Si3N4 ceramic
No full textSilicon nitride (Si 3 N 4 ) ceramic is highly desired in various engineering applications due to its exceptional properties. However, machining the Si 3 N 4 ceramic suffers setbacks due to various degrees of damage inflicted on the ceramic during machining. Studies have shown that the minimum quantity lubrication (MQL) process is a better alternative to the flood cooling lubrication system during grinding of advanced engineering ceramics. The MQL technique is a highly efficient and eco-friendly lubrication method that can be used to reduce the different types of surface and subsurface damages, while significantly lowering the consumed lubricant. In this work, the performance of the MQL and flood cooling lubrication techniques during grinding of Si 3 N 4 ceramic was investigated. The MQL nanolubricant was formed by suspending silicon dioxide (SiO 2 ) nanoparticles in environmentally friendly vegetable oil (canola oil). Also, the effect of the input parameters, i.e., feed rate, depth of cut, type of diamond wheel, and lubrication type, were investigated on the output parameters, i.e., grinding forces, workpiece surface roughness, surface damages, and wheel wear. The Taguchi mixed-level parameter experimental design (L16) was used in the design of the experiment, and the signal-to-noise ratio was used to optimize the grinding process. Furthermore, the adaptive neuro-fuzzy inference system (ANFIS) prediction method was used to predict and analyze the variation of the input parameters with the grinding forces and surface roughness. Validation experiments also indicate that the ANFIS models for the normal grinding force, tangential grinding force, and surface roughness have accuracies of 98.45, 98.58, and 96.31%, respectively
Analysis of Bacterial Communities of King George and Deception Islands, Antarctica using High-Throughput Sequencing
No full textKing George Island (KGI) and Deception Island (DCI) are members of the South Shetland Islands in Antarctica, each with their own landscape and local environmental factors. Both sites are suitable for longterm monitoring of bacterial diversity shift due to warming, as temperature rises relatively faster than East Antarctica. This study was conducted to determine and compare the baseline diversity of soil bacteria in KGI and DCI. 16S rDNA amplicons of bacteria from both sites were sequenced using Illumina next generation sequencer. Results showed that major phyla in KGI and DCI were Actinobacteria, Proteobacteria, Chloroflexi, Verrucomicrobia, Bacteriodetes and Acidobacteria. The distribution and evenness of the soil bacterial communities varied at genus level. The genera Sphingomonas sp. was predominant at both sites while the subsequent six major genera differed. Two bacterial genera, Legionella and Clostridium were also found in low abundance in both sites, both of which may contain pathogenic members. Further verification will be required to determine whether the pathogenic members of these genera are present in both sites
Densification of food waste compost: Effects of moisture content and dairy powder waste additives on pellet quality
No full textDensification of food waste compost through pelletizing is essential to increase the bulk density, expand its storability, provide ease of transportation, as well as to enable easier handling of the compost. Compost in its natural form takes up a lot of space and has a high powder dispersion rate which makes it less safe and difficult to handle. The compression of these composts into pellet forms will reduce the managing issues associated with the natural compost feedstock. In this study, the pelletizing of food waste compost by adjusting the moisture content and dairy powder waste addition was performed to evaluate the pelletization performance. The physical and mechanical properties such as moisture content, bulk density, producibility, particle density, compressive strength and moisture resistance were evaluated for the pelletized compost products. This research indicates that the addition of dairy powder additives containing lactose is very beneficial in improving the pellet production rate as well as the properties of the pellets. The pellets with lactose addition showed better producibility, better compressive strength and higher density. The presence of more solid bridges was also observed with the addition of lactose additives which crystallize and lead to stronger bonds within the pellet
Effects of Vertically Propagating Mountain Waves During a Strong Wind Event Over the Ross Ice Shelf, Antarctica
No full textWeather forecasting in the Antarctic presents many challenges, with strong wind events (SWEs) often disrupting air and field operations. Here, we study the mechanisms responsible for a SWE (maximum wind speed 22 ms -1 ) that occurred at the McMurdo/Scott Base region on the Ross Ice Shelf (Antarctica) over 12-13 October 2003. The study is based on in situ observations, satellite imagery and output from the Antarctic mesoscale prediction system (AMPS) model. The event occurred during the passage of a complex low pressure system that increased the pressure gradient between the northwest Ross Ice Shelf and the continental high, initiating a strong southerly flow. AMPS simulations as well as upper air sounding profiles from McMurdo station showed the involvement of large amplitude vertically propagating mountain waves over the area. The amplification of mountain waves by the self-induced critical level reflected all the energy back towards the surface to generate high downslope winds
Bioefficacy Evaluation of Commercial Mosquito Coils Containing Metofluthrin, d-Allethrin, d-Trans Allethrin, and Prallethrin Against Aedes albopictus (Diptera: Culicidae) in Malaysia
No full textThe bioefficacy of commercial mosquito coils containing four different active ingredients, namely metofluthrin, d-allethrin, d-trans allethrin, and prallethrin against Aedes albopictus (Skuse) (Diptera: Culicidae) from 10 states in Malaysia, was evaluated using the glass chamber method. In this study, Ae. albopictus exhibited various knockdown rates (50% knockdown time, KT 50 ), ranging from 2.50 to 5.00 min, 2.50 to 7.00 min, 3.00 to 8.00 min, and 5.00 to 17.00 min for metofluthrin, d-trans allethrin, d-allethrin, and prallethrin, respectively. Overall, all strains of Ae. albopictus were most susceptible to metofluthrin, with mortality rates >80%. On the other hand, mortality rates ranging from 5.0 to 100% were observed from all populations exposed to d-trans allethrin, d-allethrin, and prallethrin. In addition, significant correlations between KT 50 of metofluthrin and d-allethrin (r = 0.758, P = 0.011), metofluthrin and prallethrin (r = 0.676, P = 0.032), d-allethrin and d-trans allethrin (r = 0.832, P = 0.003), d-allethrin and prallethrin (r = 0.921, P = 0.000), and d-trans allethrin with prallethrin (r = 0.941, P = 0.000) were detected, suggesting some levels of cross-resistance within the pyrethroid insecticides. This study demonstrated that metofluthrin can induce high insecticidal activity in Ae. albopictus in Malaysia, followed by d-trans allethrin, d-allethrin, and prallethrin
A bench study comparing between scalpel-bougie technique and cannula-to-Melker technique in emergency cricothyroidotomy in a porcine model
No full textBackground: The ideal emergency cricothyroidotomy technique remains a topic of ongoing debate. This study aimed to compare the cannula-to-Melker technique with the scalpel-bougie technique and determine whether yearly training in cricothyroidotomy techniques is sufficient for skill retention. Methods: We conducted an observational crossover bench study to compare the cannula-to-Melker with the scalpel-bougie technique in a porcine tracheal model. Twenty-eight anesthetists participated. The primary outcome was time taken for device insertion. Secondary outcomes were first-pass success rate, incidence of tracheal trauma, and technique preference. We also compared the data on outcome measures with the data obtained in a similar workshop a year ago. Results: The scalpel-bougie technique was significantly faster than the cannula-to-Melker technique for cricothyroidotomy (median time of 45.2 s vs. 101.3 s; P = 0.001). Both techniques had 100% success rate within two attempts; there were no significant differences in the first-pass success rates and incidence of tracheal wall trauma (P > 0.999 and P = 0.727, respectively) between them. The relative risks of inflicting tracheal wall trauma after a failed cricothyroidotomy attempt were 6.9 (95% CI 1.5–31.1), 2.3 (95% CI 0.3–20.7) and 3.0 (95% CI 0.3–25.9) for the scalpel-bougie, cannula-cricothyroi-dotomy, and Melker-Seldinger airway, respectively. The insertion time and incidence of tracheal wall trauma were lower when the present data were compared with data from a similar workshop conducted the previous year. Conclusions: This study supports the use of a scalpel-bougie technique for cricothyroidotomy by anesthetists and advocates a yearly training program for skill retention
Zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS): a computerized tomography (CT) review of 1986 screws
No full textPurpose: To evaluate the zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS) patients. Methods: The scoliosis curves were divided into eight zones. CT scans were used to assess perforations: Grade 0, Grade 1( 4 mm). Anterior perforations were classified into Grade 0, Grade 1( 6 mm). Grade 2 and 3 (except lateral grade 2 and 3 perforation over thoracic vertebrae) were considered as ‘critical perforations’. Results: 1986 screws in 137 patients were analyzed. The overall perforation rate was 8.4% after exclusion of the lateral perforation. The highest medial perforation rate was at the transitional proximal thoracic (PT)/main thoracic (MT) zone (6.9%), followed by concave lumbar (6.7%) and convex main thoracic (MT) zone (6.1%). The overall critical medial perforation rate was 0.9%. 33.3% occurred at convex MT and 22.2% occurred at transitional PT/MT zone. There were 39 anterior perforations (overall perforation rate of 2.0%). 43.6% occurred at transitional PT/MT zone, whereas 23.1% occurred at concave PT zone. The overall critical anterior perforation rate was 0.6%. 5/12 (41.7%) critical perforations occurred at concave PT zone, whereas four perforations occurred at the transitional PT/MT zone. There were only two symptomatic left medial grade 2 perforations (0.1%) resulting radiculopathy, occurring at the transitional main thoracic (MT)/Lumbar (L) zone. Conclusion: Overall pedicle perforation rate was 8.4%. Highest rate of critical medial perforation was at the convex MT zone and the transitional PT/MT zone, whereas highest rate of critical anterior perforation was at the concave PT zone and the transitional PT/MT zone. The rate of symptomatic perforations was 0.1%
Surfactant-Free Direct Access to Porphyrin-Cross-Linked Nanogels for Photodynamic and Photothermal Therapy
No full textPhotosensitizing nanogels were obtained through a surfactant-free single-step protocol by using a porphyrin-based cross-linker for stabilizing self-assembled nanosized aggregates of thermoresponsive copolymers. Nanogels with varying amounts of porphyrin retained the singlet oxygen generation ability of the porphyrin core and were also capable of inducing temperature increase upon irradiation at 635 nm. Photoinduced killing efficiency was tested against three cell lines: human breast adenocarcinoma (MDA-MB-231 and MCF7) and pancreatic adenocarcinoma (AsPC-1) cells, and a predominant photodynamic mechanism at 450 nm and a mixed photodynamic and photothermal effect at 635 nm was observed. This innovative access to photosensitizing nanogels is a proof of concept, and opens new perspectives toward the preparation of optimized nanophotosensitizers