Absence Of Cracking Research Articles

INTENTIONAL REPLANTATION AFTER PERIAPICAL CYST TREATMENT: A CASE REPORT OF PERSISTENT LESION

Intentional reimplantation (IR) is the last alternative for some cases of endodontic retreatment with persistent lesions. In the related case, a 53-year-old male patient presented recurrence of periapical lesions on teeth 11 and 21. Computed tomography showed 2 distinct lesions related to the apex of each tooth. No cracking or root fracture was observed. It was decided to perform a new apicoectomy, and diagnosis of the collected tissue was inflammatory cyst. Tooth 11 presented a fistula 3 months after the procedure. Therefore, IR was considered. The root was extracted and observed under a microscope, confirming absence of cracking. Immediately, retrofilling and reimplantation were performed. The case has been in observation for 4 months with no sign of relapse. In the literature there are scarce reports of cases of IR performed after the removal of periapical cysts. However, this approach can be carried out for dental preservation.

Wooden Nano-Composite Materials and Prospects of their Application in Wooden Housing Construction

Nano-composite material is a completely new class of material that combines wood pulp and some porous materials of artificial and natural origin. This is an artificially created material consisting of a polymer matrix of the porous natural or synthetic material. The number of micro or macro-pores in the composite can be different for different wood species variety of micro and macro capillaries varying in average from 25 to 35% of the wood volume. The change in wood properties occurs at the structuring of water-insoluble molecules smaller than 3 nm and that is a part of the filler. Industrial technology of deep processing of wood-based nanotechnology allows the manufacture of new products such as laminated wood structures with nano-device that have properties not existing in nature: 1. The wood becomes hydrophobic, it is characterised by almost complete lack of absorption by the body of the wood, which leads to almost full, the lack of swelling and the change of the geometrical sizes of the material; 2. The absence of cracking. As the penetrating substance is evenly distributed between micro and macro pores and uniformly fills all the frame structure, there are additional internal stresses, typical for products made of natural wood; 3. The use of such technology ensures high 10-25% of the density if you increase strength by 20%, which also increases the seismic resistance and mi CNTI products and structures.

PEACH BREEDING PROGRAMME FOR NEW CULTIVARS AND DIFFERENT TRAITS - POMOLOGICAL AND PHENOLOGICAL DATA ANALYSIS WITH A RANKING METHOD

The main goals of the breeding programme developed at CRA-FRU are presented. These include the selections of new types of peaches and nectarines. We considered traits specifically limited to the fruit such as: flat shape, low-acid taste, anthocyaninless and bloody flesh. All the descriptive (pomological, phenological, agronomical) data, collected over 20 years on 535 advanced selections (365 peaches and 170 nectarines) were analyzed using a ranking method, in order to depict the best performing individuals. The most important characteristics in the evaluation were: weight, shape and over-color (with a higher ranking score), taste, firmness, fruit symmetry, yield and ripening period. Among the 365 peach selections, 42 flat peaches, 21 anthocyaninless, 39 bloody fleshed and 5 low acid were identified for further analysis. Among the 170 nectarines, 8 flat, 1 anthocyaninless, 2 low acid, and 20 bloody fleshed selections were identified for further analysis. In order to select the most promising individuals, specific multi-criteria ranking method was adopted for each fruit type: for the flat shape, the absence of cracking and other damages; for low acid, the Soluble Solid Concentration (SSC); for the anthocyaninless flesh, the white-cream skin and flesh coloration and the perception of low acid taste; for the bloody flesh, the red flesh color higher than 35%, the SSC content and the lack of cracking and rust were considered. The last step was to exclude the contemporaneous selections and those that ripen at the same time as the licensed or commercial cultivars. Using above criteria it was possible to discard about 90% of the selections. The pomological and phenological characteristics of the top peach selections are presented.

Damage Tolerant Evaluation of Interlaminar Delamination in a High Strength GFRP Helicopter Rotor Component

The allowable defect size for a helicopter rotor hub made of high strength glass fiber reinforced plastic (GFRP) was evaluated based on the damage tolerant design method. The threshold values of the energy release rate range, ΔGth, for fatigue crack propagation were established under the pure and mixed modes of I, II and III for GFRP. An initial delamination crack was located at various positions in rotor hub. The energy release rate range, ΔG, was calculated for each position using the finite element method. The allowable defect size was determined from the threshold values and the energy release rate range, ΔG. The maximum energy release rate ranges of mode II and III, ΔGII and ΔGIII, for an internal elliptic crack were generated at the crack front edge in the centrifugal direction, and in the perpendicular direction. The maximum value of ΔGII is large than that of ΔGIII, but the threshold value of mode III, ΔGIIIth, is smaller than that of mode II. This suggests that, for an internal elliptic crack, the energy release range at the crack front edge in the centrifugal direction is critical for damage tolerant design. The region where the allowable defect size was determined to be the smallest corresponded to the position that showed the peak shear stress in the absence of cracking, which, for the hub in this study, was the center of the plate thickness at the thickness change division.

POLYMERIC ACID FOR THIN FILM APPLICATIONS

ABSTRACT Propyl and butyl half esters of the alternating copolymer isobutylene/maleic anhydride (IB/MAn) are polymers of high acid content (4.67 and 4.38 milliequivalent acid/g polymer). These polymers exhibit good physical performance in thin films, such as absence of cracking and minimal curl. The anhydride ring of the copolymer IB/MAn is opened in refluxing alcohol at atmospheric or elevated pressure; conversion is monitored by an IR probe (1783 vs. 1733 cm−1). The polymers are stable up to about 50 °C. Weight loss corresponding to the reversion to the anhydride structure is observed at higher temperature, with concurrent increase of anhydride resonances in the IR. Thermal stability of the half esters is similar to that of alkyl half esters of the alternating copolymers ethylene/maleic anhydride (EMA) and methyl vinyl ether/maleic anhydride (Gantrez® AN 119). The 1-propanol solution of the propyl half ester of IB/MAn copolymer is a shear thinning fluid, a significant advantage when coating at high speeds.

On Strain-Enhanced Diffusion in Metals. III. Interpretation of Recent Experiments

A critical interpretation of recent experimental results on the effects of plastic deformation on diffusion is carried out with the aid of the results established in the preceding Parts I and II. Attention is focused on experiments carried out at elevated temperatures (higher than half the absolute melting temperature) in which diffusion occurred over macroscopic distances. The results are discussed in terms of the following possible causes of apparent enhanced diffusion: (1) generation and migration of excess point defects during deformation; (2) short-circuiting along static or moving dislocations or grain boundaries created in the deformation; (3) short-circuiting along cracks created in the deformation; and (4) experimental difficulties associated with interface roughness. Causes (3) and (4) are of little basic interest but must be considered in any survey of experimental results. Fourteen experiments in all are considered. Ten of these experiments showed no apparent enhancements within the expected experimental error of about 50% in the diffusivity. In one of these ten experiments a large enhancement was reported, but is is shown that this was due solely to an error in mathematical analysis. Two of the experiments showed large apparent enhancements, and it is shown that they were almost certainly due to (4). One of the experiments showed apparent enhancements due to (3) but showed no enhancement in the absence of cracking. One of the experiments showed enhancements which, it is concluded, are not inconsistent with present knowledge of (2). [Very recent work by Brown and Blackburn (unpublished) indicate that at least some of the enhancements in this experiment may have been due to (4)]. It is generally concluded that in no case has a diffusion enhancement been detected due to the generation of excess vacancies. However, enhancement in one case may have occurred as a result of short-circuiting. These results are consistent with other high temperature deformation phenomena, e.g., creep kinetics, and are also consistent with the point defect and short-circuiting models developed in the preceding Parts I and II which predict very small effects due to point defects and possibly larger effects in certain cases due to short-circuiting.

Absence of cracking of stressed rubber by free radicals

Absence of cracking of stressed rubber by free radicals