Pulse-by-pulse optical observation of laser-irradiated thin glass substrate using oil-immersion microscopy

To study the formation mechanism of laser-induced periodic surface structures, we carried out a pulse-by-pulse optical observation of laser-induced surface morphological changes on thin glass substrates. We adopted oil-immersion microscopy, which has a higher spatial resolution than dry microscopy, and the laser was irradiated from the air side. A thin transparent substrate of coverslip was used as the sample. When a scratched coverslip was irradiated with focused subnanosecond laser pulses of 1.064 µm wavelength, periodic structures occasionally appeared in the flat region near the focus, with a period of about 0.55 μm.

Devising a cost-effective method to improve the specificity and sensitivity of malaria detection

Background: It has always been a challenge to increase the concentration of malaria parasites in blood without compromising on specificity. The conventional thick smear method is a good sensitive tool. But the disadvantage is that a lot of expertise and experience is needed to perform this. A pilot study was undertaken to improvise the quantitative buffy coat (QBC) method so that the advantages of both thick and thin smears could be combined. Methods: Used QBC capillary tubes were washed off the blood and the dye and thoroughly cleaned and dried. The floats were preserved. Blood samples of ten malaria positive patients collected already in EDTA bottles were drawn onto the washed and dried QBC capillaries. The float was re-inserted and centrifugation done as recommended by the QBC manufacturers. The capillary tubes were broken with the aid of a diamond pencil at the area were parasites infested cells were most likely to be seen ie just below the buffy coat area. Smears were made onto a slide with this material and stained using the conventional Romanowsky method of staining. Ordinary microscopy was carried out and parasitaemia were quantified as number per oil immersion field and the results were compared with the recorded thin film reports. Five known negative controls were treated similarly. Results: Parasites’ number was found to be on an average ten times higher per oil immersion field compared to the conventional methods. Negative controls yielded valid outcomes. Conclusion: This preliminary study promises to be a useful tool in screening for malaria in endemic areas where resources are limited. It also adds to the specificity compared with the original QBC method. Larger study involving more samples is required to further validate the results. Any easy method (preferably automated) to cut the capillary tube thereby eliminating the risk of infection to the operator would help a long way in making the method more user friendly.

Influence of Lubricant Supply on Thermal and Efficient Performances of a Gear Reducer for Electric Vehicles

The amount of lubricating oil in a gear reducer greatly influences components' temperature and efficiency of the reducer. A thermal network simulation model of a gear reducer for electric vehicles based on AMESim software was built for thermal and efficiency analysis of the reducer, where heat production and transfer processes of each component in the reducer are considered. Moreover, secondary development sub-models were developed to real timely calculate the convection coefficients based on different lubricating oil temperatures and working conditions. Next, the experiments were conducted to verify the developed model regarding transmission efficiency and lubricating oil equilibrium temperature in the reducer. The deviation between the numerical and experimental results is below 5%, which indicates high accuracy of the developed thermal network model. Thereafter, efficiency and heat balance simulation tests under different working conditions were performed to determine an optimal lubricating oil supply which is 14 mm gear-oil-immersion oil supply in this study. Finally, a comparison between the reducer with the optimal oil supply and that with normally used 22 mm gear-oil-immersion supply in the NEDC cycle in low temperature was conducted. The reducer with the optimal oil supply shows 1.032% energy saving. The method presented in this paper provides a good guide to design and optimization of the gear reducer for electrical vehicles.

Helminthes Parasites of Clarias gariepinus in Abraka Delta State, Nigeria

Fish is significant as a vector of disease pathogen of human and animals. The study of the helminthes parasites of Clarias gariepinus in Abraka was carried out to investigate the occurrence, prevalence and intensity of helminthes parasites in Clarias gariepinus; and to compare the helminthes parasites burden of the wild and cultured Clarias gariepinus in Abraka fresh water. A total number of four hundred and nine (409) Clarias gariepinus were examined. Collection of fish samples was done monthly for twelve months. The external parts of each fish were examined with a hand lens for the occurrence of helminthes parasites. Portions of the muscles were also teased apart in saline water and examined under the microscope first at x 40 and later x 100 oil immersion. Organs of the body were examined separately in petri dishes containing normal saline. The different groups of parasites recovered were preserved in formaldehyde and identified using prescribed methods. Of the 409 C. gariepinus examined, 172 were infected, showing an infection rate of 42.1%. C. gariepinus from the wild had a higher prevalence of 31.1% while those from culture ponds had a lower prevalence of 11%. A total of 485 parasites were recovered, comprising of 113 trematodes and 372 nematodes which represents 23.3% and 76.7% respectively. Identified trematodes included Diplosomum sp., Macrogyrodactylus sp., and Quadriancanthus sp., while namatodes included Procamallanus sp. and an Ascarid nematode. The highest intensity of infection of 3.11 was recorded in the Ascarid nematode while the least of 1.25 came from Diplostomum sp. in C. gariepinus caught from the wild. Although, there appears to be a lack of reported cases of the occurrence of the ascarid nematode that was recovered from the muscles of C. gariepinus in literature, it is evident from this study that it is a common endoparasite of the African catfish in Abraka freshwater.

Churning power loss of the intermediate gearbox in a helicopter under splash lubrication

Based on computational fluid dynamics, a two-phase flow model was established to calculate the churning power loss of the spiral bevel gears under splash lubrication. The error between the simulation results and experiment results is only 7.04%. Taking a certain helicopter as an example, the churning power loss of the intermediate gearbox is ∼2.6051 kW, accounting for ∼1.93% of the input power. Besides, the motion mechanisms of free flow, ejection flow and splashing flow of the spiral bevel gear were investigated. The influences of the rotational speed and oil immersion depth on the churning power loss were analysed. The rotational speed and oil immersion depth of the intermediate gearbox should be in the range of 3000–5000 r/min and 17–26 mm, respectively, which can ensure sufficient lubrication and low churning power loss.

Nanoscopic live electrooptic imaging

A door to the nanoscopic domain is opened regarding real-time visualization of electric field distributions and dynamics. Through the use of a live electrooptic imaging system with an oil-immersion objective lens and a highly thinned electrooptic sensor film, a minimum linewidth of 330 nm and a minimum peak splitting of 650 nm in real-time electric field video images have been successfully demonstrated. In addition, room to improve the resolution is noted, while a few problems that need to be solved are discussed, including an effect caused by optical interference.