Problem of glass grinding and polishing process?5 answersThe problem with glass grinding and polishing processes lies in the generation of defects such as flaws, cracks, and sub-surface damage (SSD). These defects impact the overall strength and quality of the glass, necessitating subsequent polishing steps to remove them. High material removal rates during grinding contribute to deeper SSD, requiring efficient methods to eliminate it for precise optical components. Overlaps in tool influence functions during polishing can lead to mid-spatial frequency errors, which need to be addressed to maintain surface quality. The challenge is to develop effective polishing techniques that not only remove defects but also minimize surface figure degradation and maximize material removal rates. Improving the surface quality through specialized polishing cup wheels and intelligent machining techniques can enhance the strength and quality of glass edges.
What are some of the challenges of orthodontic rotation?5 answersOrthodontic rotation poses several challenges. One challenge is the management of severe rotation, especially when cortical anchorage occurs. Conventional methods require excessive treatment time, rely on patient compliance, and can cause root resorption. Another challenge is defining the centers of rotation clinically, as observed tooth behavior can vary widely. Factors such as the angle of load application and the exact geometry of the alveolar process significantly influence tooth movement. Severe tooth rotations can cause cosmetic problems, gingival recession, and traumatic occlusion. Removable appliances can be used to treat severe rotations and prevent complications in future orthodontic treatment. Orthodontic treatment itself has the potential to cause damage to dental enamel, including enamel fractures, demineralization, and wear or erosion due to contact with brackets or bacterial biofilm. Additionally, factors other than straightening of supracrestal fibers may be responsible for relapse of rotated teeth.
What are some of the mechanical defects that can occur during wafer polishing?5 answersDuring wafer polishing, some mechanical defects that can occur include the formation of micro-defects such as particle residues and scratches on the silicon surface. These defects can be reduced by using surfactants and water-soluble polymers to improve the wettability of the slurry and reduce the flocculation of abrasive particles. Another defect that can occur is the presence of defects on the wafer backside, which can be detected and repolished if their level is within an allowable range. Additionally, the strength of wafers can be affected by the damage induced during grinding and polishing, which can impact the stability of diced ultra-thin chips. Finally, in indexed polishing methods, there can be a characteristic haze irregularity that occurs during the polishing step and between the completion of polishing and the beginning of the detachment operation, which can be effectively prevented.
How can acetic bacteria be identified in plates?5 answersAcetic acid bacteria can be identified in plates using different methods. One approach is to use molecular biological methods, such as the 16S-23S rRNA gene ITS regions and MALDI-TOF MS. Another method involves using a modified Frateur medium combined with a water solution of nystatin to isolate acetic acid bacteria from fermenting fruit. Additionally, a simple screening method based on the ability of diacetyl and acetoin to form a red insoluble complex with α-naphthol in the presence of creatine can be used to discriminate between citrate utilizing and non-utilizing bacteria. Furthermore, a novel plate assay has been developed for the detection of indole-3-acetic acid (IAA) in bacterial strains, which is rapid, cheap, and accurate. Lastly, (GTG)(5)-PCR fingerprinting can be used to classify and identify acetic acid bacteria based on their taxonomic and phylogenetic relationships.
Can ceramic plates get moldy?4 answers
How do you keep ceramic plates from warping?7 answers