Effect of Water-Based Disinfectants or Air-Drying on Dimensional Changes in a Thermoplastic Orthodontic Aligner

The polymer structure of thermoplastic materials currently used to make aligners is altered by the oral conditions and this negatively affects their capacity to move teeth. This study aimed to compare different options for storing aligners when not in use by superimposing successive 3D images to identify which storage method least affects material shape and weight. Fifty PET-G aligners, produced using the CA Digital method, were divided into four groups (1A, 1B, 1C, and 2D) and were stored for 18 h a day in artificial saliva at 37 °C. Then, to mimic their storage conditions when not in use, aligners in group 1A were immersed for the remaining 8 hours a day in bicarbonate solution, those in group 1B in chlorhexidine solution, those in group 1C in distilled water, and those in group 2D were stored dry. The samples were scanned at the baseline (before the immersion cycles began) and again two weeks later. The digital scans were superimposed and the median deformation, its variability, and weight differences were recorded for each group. Statistical analysis showed aligner deformation (expansion) in all three groups stored in wet conditions, with a statistically significant difference between groups 1A and 1C. Aligners in group 2D shrank slightly, and to a significantly greater degree with respect to group 1C. Variability in the degree of deformation was similar among the three groups stored in wet conditions, but significantly greater in group 2D. Weight gains were recorded in all four groups, the smallest in group 2D and the largest in group 1A. Storing aligners in dry conditions promoted lower deformation in the material, involving a slight shrinkage, whereas wet storage conditions caused an expansion of the aligner, especially when distilled water is used.

Complex ⁴⁰Ar/³⁹Ar age spectra from low metamorphic grade rocks: resolving the input of detrital and metamorphic components in a case study from the Delamerian Orogen

Low metamorphic grade rocks contain both detrital minerals and minerals newly grown or partly recrystallised during diagenesis and metamorphism. However, rocks such as these typically yield complex 40Ar/39Ar age spectra that can be difficult to interpret. In this study, we have analysed a suite of variably deformed rocks from a region of low metamorphic grade within the c. 514–490 Ma Delamerian Orogen, South Australia. The samples analysed range from siltstone and shale to phyllite and all contain either muscovite or phengite determined by hyperspectral mineralogical characterisation. Furnace step heating 40Ar/39Ar analysis produced complex apparent age spectra with multiple age components. Using the concept of asymptotes that define minimum and maximum ages for different components, we interpret the age spectra to preserve a range of detrital mineral ages, along with younger components related to either cooling or deformation- induced recrystallisation. Two samples contain Mesoproterozoic detrital age components, up to c. 1170 Ma, while the c. 515 Ma Heatherdale Shale which has both c. 566 Ma and c. 530 Ma detrital components. All samples contain younger lower (younger) asymptotes in the age spectra defined from multiple heating steps that range from c. 476 to c. 460 Ma. One interpretation of these younger ages is that they are caused by post-metamorphic cooling. However, the shape of the age spectra and the degree of deformation in the phyllites suggest the ages may record recrystallisation of detrital minerals and/or new mica growth during deformation. Potentially these c. 476 to c. 460 Ma ages suggest deformation in the upper portion of the orogen was facilitated by movement along regional faults and shear zones up to around 20 million years after the cessation of deformation in the high-metamorphic grade regions of the Delamerian Orogen.

The Study of Bending and Twisting Input Modalities in Deformable Interfaces

The deformable input provides users with the ability of physical operation equipment to interact with the system. In order to facilitate further development in flexible display interactive technology, we devised FlexSheet, an input device that can simulate the deformation environment. This paper presents two forms of deformation input, bending and twisting, with regard to three selection techniques. We conduct a controlled experiment to select discrete targets by combining two input forms and three selection strategies, taking into account the influence of visual feedback. Further, we use the deformation angle to reflect the degree of deformation and map it to the experimental variables. In accordance with the experimental results, we analyze the experimental performance under three evaluation indexes and prove the viability of our selection technology in bending and twisting input modes. Finally, we provide suggestions on the control level in bending and twisting input modes, respectively.

Research of Technology For Production Deformed Semi-Finished Products From Chip Waste of Aluminum Alloys And Study Properties of The Obtained Products

The results of studies of some methods of obtaining longish deformed semi-finished products in the form of rods and wires from chips of aluminum alloys 6063 and AlSi12 excluding the melting process during their implementation are presented. At the same time, the main methods used powder metallurgy (briquetting), metal forming (extrusion and drawing), and heat treatment (annealing). Using the developed general technological scheme of thermal deformation processing of chip waste from aluminum alloys, experimental studies of the technology of production of longish deformed semi-finished products from high-quality chips of alloys 6063 and AlSi12 have been carried out. The mechanical properties of metal obtained from shavings of experimental alloys of briquettes, rods, and wires were determined. The change in the structure of semi-finished products at all technological stages of processing was investigated. Computer simulation has been carried out, according to the results of which the regularities of temperature change, degree of deformation, and relative density in the volume of the deformation zone for semi-finished products obtained by the method of combined rolling-extrusion of a porous billet from briquette chips of 6063 alloy. As well as the degree of deformation, average normal and tangential stresses in the zone have been established. Deformation depends on the conditions of contact friction when drawing a wire from this alloy. Using the results of computer simulation, the proposed routes for drawing wire from extruded rods of chips of 6063 and AlSi12 alloys were experimentally tested and with their help, experimental batches of products were obtained for various industrial purposes.

Deformed and stressed states of materials at the rolling of three layer stacks, dislocation structure of inner layer – nickel foil

The deformed and stressed states during rolling of a three-layer stack from various materials with a nickel foil inner layer are considered. The technique of determining the density of dislocations is described. The data about the influence of deformation conditions on the distribution and density of dislocations during rolling of nickel foil in various stacks are presented, including the registration or determination of the dislocation structure of nickel foil before deformation and at various degrees of deformation. It is shown that the mechanical scheme of deformation of the inner layer of the stack, namely, the deformation of the nickel foil by non-uniform compression with shear, has a decisive influence on the development of the dislocation structure and properties. It is established that the dislocation density is determined not only by the degree of deformation, but also by a scheme of the deformed and stressed state of matter, and for the case of shear deformation with increasing degree of deformation the dislocation density increases more rapidly than in the case of tensile strain or compression without shear; the result of shear deformation is a significant refinement of the structure of materials: with increasing degree of plastic deformation of the material a three-dimensional cellular network of dislocation is formed, wherein the borders of cells are formed by tangles of dislocations. With increasing degree of deformation, the density of dislocations at the cell boundaries increases, and the size of the cells decreases; in this case, the areas inside the cells of the dislocation network are always free of dislocations. The obtained results allow recommending the schemes with shear deformation for new promising processes of production of materials with unique properties.

Quasi-Static Research of ATV/UTV Non-Pneumatic Tires

The non-pneumatic tire (NPT) is a type of wheel whichdevelopment is related to the beginning of automotive development. The non-pneumatic tire (NPT) is a type of tire that does not contain compressed gases or fluid to provide directional control and traction. Nowadays, this type of wheel is more and more often used in special purpose vehicles, e.g., in military vehicles and working machines. The main feature of the non-pneumatic tire is a flexible support structure (including the part of the wheel between the tread and the rim). This paper presents the results of research aimed at determining the influence of the geometry of the NPT’s (intended for All-Terrain Vehicle - ATV / Utility Task Vehicle - UTV) load-bearing structure on its quasi-static directional characteristics. The experimental tests included the determination of the radial stiffness of research objects on a non-deformable flat surface and on a single obstacle, as well as the determination of the degree of deformation for the elastic structure and belt. The significant influence of the elastic structure’s shape and the elastomer, as the material forming the NPT, on its radial stiffness was revealed.

Optimizing the High-Performance Milling of Thin Aluminum Alloy Plates Using the Taguchi Method

Most aerospace parts are thin walled and made of aluminum or titanium alloy that is machined to the required shape and dimensions. Deformation is a common issue. Although the reduced cutting forces used in high-speed milling generate low residual stress, the problem of deformation cannot be completely resolved. In this work, we emphasized that choosing the correct cutting parameters and machining techniques could increase the cutting performance and surface quality and reduce the deformation of thin plates. In this study, a part made of a thin 6061 aluminum alloy plate was machined by high-speed milling (HSM), and a Taguchi L16 orthogonal array was used to optimize the following parameters: linear velocity, feed per tooth, cutting depth, cutting width, and toolpath. The impact of cutting parameters on the degree of deformation, surface roughness, as well as the cutting force on the thin plate were all investigated. The results showed that the experimental parameters for the optimal degree of deformation were A1 (linear velocity 450 mm/min), B1 (feed per tooth 0.06 mm/tooth), C1 (cutting depth 0.3 mm), D4 (cutting width 70%), and E4 (rough zigzag). Feed per tooth was the most significant control factor, with a contribution as high as 63.5%. It should also be mentioned that, according to the factor response of deformation, there was a lower value of feed per tooth and less deformation. Furthermore, the feed per tooth and the cutting depth decreased and the surface roughness increased. The cutting force rose or fell with an increase or decrease of cutting depth.

Research on Action of Bone Marrow Stromal Cells (BMSC) Modified by Toll-Like Receptor for Myocardial Function of Rats with Myocardial Infarction (MI)

MI could affect myocardial function seriously. The action and mechanism of BSMC modified by the transplantation of Toll-like receptor on myocardial function of rats with MI was studied. The sixty SD rats were divided into sham-operation group and model group randomly. The isolated and cultivated BMSC was divided into three groups such as group with added by TLR4 agonist, group with added by TLR-4 antagonist as TAK-242, group with only BMSC. The model of rats with MT was established in model group. BMSC in different group was transplanted into rats respectively. The cardiac function of rats in sham-operation group and model group was observed. The distribution condition of surface molecule in BMSC was detected by FCM. There was expression CD44 (+), CD54 (+), CD90 (+), no expression CD34 (−) from results. It could indicated that BMSCs with high purity was cultivated successfully. The high MT expression was affected by TLR-4 generally which could also illustrate the degree of deformation and necrosis of cardiac muscle cell, could be enhanced in established rat model because of negative regulatory action. The zone of MI in rats could be amplified by TLR-4. The cytobiological function of BMSC could be adjusted by TLR-4 through the transplantation of TLR-4 after there was MI in rats. The cytobiological function of BMSC could be adjusted by TLR-4 through modification of the transplantation of TLT-4 in rats after there was MI in rats. The BMSCs modified by high TLR-4 expression had negative regulatory action on the treatment on MI.

Behavior of Cell Passing Through Micro Slit Between Micro Machined Plates

Deformation of each cell, as it passes through the micro-slit in the flow channel, has been investigated in vitro. A slit with a rectangular cross section (height 10 μm, width 0.4 mm, length 0.1 mm) was made in the center of the flow path by photolithography technique. Myoblasts (C2C12: mouse myoblast cell line) were used for the test. The flow rate of the medium, in which the cells were suspended, was controlled by a pressure head between the inlet and the outlet. Deformation of each cell passing through the micro-slit was observed with an inverted phase contrast microscope. Using the contour of the image of each cell passing through the slit intermittently, several parameters were analyzed: the two-dimensional projected area, the degree of deformation by ellipse approximation, and the deformation direction. The experimental results show that elongation of the cell in the slit tends to decrease the area of the cell.