Experimental Investigations into Assessment of Thrust Force and Temperature in Bone Drilling

Drilling of bone is a challenging task for surgeons due to its effect on bone tissues. During drilling, it is noted that the temperature of bone increases. This increase in temperature if above 47°C causes thermal necrosis. Experiments were conducted to study the effect of input drilling parameters and drill bit parameters on bone health. To plan experiments a full factorial design method was used. An analysis is done on the effect of input parameters on thrust force and temperature of bone. The analysis of results shows an increase in thrust force and temperature when the feed rate increases and the spindle speed decreases. Further, the analysis of results shows an increase in thrust force and temperature when point angle increases and helix angle decreases. The increase in thrust force results in temperature rise. Scanning electron microscopy is done to analyze the surface topography of drilled hole. SEM image analysis shows an increase micro-crack in the drilled area when the thrust force and temperature increases.

Recycled Mortars with Ceramic Aggregates. Pore Network Transmutation and Its Relationship with Physical and Mechanical Properties

The porosity of mortars with recycled ceramic aggregates (10, 20, 30, 50, and 100% as a replacement of natural aggregate) was evaluated and analyzed using three different techniques. The results of gas adsorption (N2), Scanning Electron Microscopy (SEM) image analysis and open porosity allowed establishing the relationship between the recycled aggregate content and the porosity of these mortars, as well as the relationship between porosity and the physical and mechanical properties of the mortars: absorption, density, compressive strength, modulus of elasticity, and drying shrinkage. Using the R2 coefficient and the equation typology as criteria, additional data such as Brunauer, Emmett, and Teller (BET) surface area (N2 adsorption) established significant correlations with the mentioned properties; with SEM image analysis, no explanatory relationships could be established; and with open porosity, revealing relationships were established (R2 > 0.9). With the three techniques, it was confirmed that the increase in porosity is related to the increase in the amount of ceramic aggregate; in particular with gas adsorption (N2) and open porosity. It was concluded that the open porosity technique can explain the behavior of these recycled mortars with more reliable data, in a simple and direct way, linked to its establishment with a more representative sample of the mortar matrix.

Nitzschia taikiensis sp. nov. (Bacillariophyta) – a new brackish diatom from the Toberi River marsh in the eastern Hokkaido, Japan

Nitzschia taikiensis sp. nov. is a brackish diatom species found in the Toberi River marsh, eastern Hokkaido, Japan. This species has characteristics similar to Nitzschia subamphioxoides Hustedt, which was originally described by Hustedt in 1959. In the present study, we conducted a comparative morphological analysis of N. taikiensis and N. subamphioxoides. The obtained results showed that they are different species. Sampling sites of N. taikiensis were located in salt marsh environments with very low salinity (1-5‰), acidic pH (5.2-5.9) and high mud content (95.0-97.5%). Identification of this species was relatively easy based on LM and SEM image analysis of its frustule features, such as the external form and stria density. This species has not been previously reported in Japan, which could be attributed to the reduction or loss of Japanese freshwater and salt marsh environments in the coastal areas, resulting from urban and industrial development.

Influence of Complex SiF62− Ions on the PEO Coatings Formed on Mg–Al6–Zn1 Alloy for Enhanced Wear and Corrosion Protection

The present study was carried out to explore the effect of SiF62− incorporation and concentration on the plasma electrolytic oxidation (PEO) coatings formed on AZ61 Mg alloy. The coatings were prepared using electrolyte solution with various concentration of Na2SiF6 (0.0–0.7 g/L). Highly compact coatings with minimum porosity were obtained for an optimum concentration of Na2SiF6 ~0.3 g/L added into the electrolyte. The highest corrosion resistance, ~2.04 × 105 Ω·cm2, was obtained for 0.3 g/L of Na2SiF6, in addition to its superior anti-wear properties. However, it was found from the scanning electron microscope (SEM) image analysis that increasing concentration above 0.3 g/L, could cause severe breakdown in the inner layers, and thus the said coatings could not withstand effectively against wear and corrosion.

Comparative analysis of shrew tooth pigmentation using energy-dispersive X-ray spectroscopy (EDX)

The pigment of tooth enamel is an important odontological character for character for assessing Soricidae taxonomy and phylogeny. This paper describes the original observations of ‘pigment patterns’ (PPt) and ‘visible pigment’ (VPg) in fossil beremendiin shrews in light of the “differential pigmentation” found using UV detection and EDX analysis. The term “differential pigmentation” was used to describe the irregular pigmentation on the teeth of extinct Nesiotites (Neomyini). Our analysis of fossil and recent specimens reveals different reasons for differential pigmentation formation. The first reason is related to fossilization, namely, the chemical alterations of the buried specimen. The second reason is related to a developmental disorder, namely, the enamel organ disorder, which locally stops forming the twin enamel layer. Our original results and published data from EDX analysis of the enamel elemental content and SEM-image analysis of the enamel microstructure again raise the question of a relationship between ferruginous pigmentation and enamel microstructure. Further studies of the enamel structure and pigment chemical composition of red-toothed shrews compared to white-toothed shrews are required.

Application of Biocides and Super-Absorbing Polymers to Enhance the Efficiency of Filtering Materials

Studies on the functionalization of materials used for the construction of filtering facepiece respirators (FFRs) relate to endowing fibers with biocidal properties. There is also a real need for reducing moisture content accumulating in such materials during FFR use, as it would lead to decreased microorganism survival. Thus, in our study, we propose the use of superabsorbent polymers (SAPs), together with a biocidal agent (biohalloysite), as additives in the manufacturing of polypropylene/polyester (PP/PET) multifunctional filtering material (MFM). The aim of this study was to evaluate the MFM for stability of the modifier’s attachment to the polymer matrix, the degree of survival of microorganisms on the nonwoven, and its microorganism filtration efficiency. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used to test the stability of the modifier’s attachment. The filtration efficiency was determined under conditions of dynamic aerosol flow of S. aureus bacteria. The survival rates (N%) of the following microorganisms were assessed: Escherichia coli and Staphylococcus aureus bacteria, Candida albicans yeast, and Aspergillus niger mold using the AATCC 100-2004 method. FTIR spectrum analysis confirmed the pre-established composition of MFM. The loss of the active substance from MFM in simulated conditions of use did not exceed 0.02%, which validated the stability of the modifier’s attachment to the PP/PET fiber structure. SEM image analysis verified the uniformity of the MFM structure. Lower microorganism survival rates were detected for S. aureus, C. albicans, and E. coli on the MFM nonwoven compared to control samples that did not contain the modifiers. However, the MFM did not inhibit A. niger growth. The MFM also showed high filtration efficiency (99.86%) against S. aureus bacteria.

Tribological Analysis by Concentration Effect of Boron Carbide and Graphite on the Aluminum Composites

Aluminium matrix composites (AMCs) are indispensable materials used extensively in the aerospace and automobile industries and are highly endorsed due to their good mechanical properties. In this paper, various compositions of the AMCs were fabricated, tested and analyzed using pin on disc tribometer test to understand the tribological behaviour and wear mechanism properties. The volume percentages of the Aluminium composite reinforced with boron carbide and graphite present in the form of Al-B4C-Graphite are Al-B4C (5%)-Graphite (5%), Al-B4C (10%)-Graphite (5%), Al-B4C (5%)-Graphite (15%), Al-B4C (10%)-Graphite (15%), Al-B4C (15%)-Graphite (15%). Loads were varied in steps of 10N, from 10N to 50N while the sliding velocity was correspondingly set as 0.7, 1.4 and 2.1m/s. SEM image analysis was conducted to understand surface tribology after wear tests. The composite Al-B4C (15%)-Graphite (15%) exhibited best wear resistance which can be credited to the bearing capacity of boron carbide particles and adherent graphite layer.