Dural tear repair surgery comparative analysis: a stitch in time saves nine

Purpose A dural tear is a common iatrogenic complication of spinal surgery associated with a several post-operative adverse events. Despite their common occurrence, guidelines on how best to repair the defect remain unclear. This study uses five post-operative outcomes to the compare repair methods used to treat 106 dural tears to determine which method is clinically favourable. Methods Data were retrospectively collected from Southampton General Hospital’s online databases. 106 tears were identified and grouped per repair method. MANOVA was used to compare the following five outcomes: Length of stay, numbers of further admissions or revision surgeries, length of additional admissions, post-operative infection rate and dural tear associated neurological symptoms. Sub-analysis was conducted on patient demographics, primary vs non-primary closure and type of patch. Minimal clinically important difference (MCID) was calculated via the Delphi procedure. Results Age had a significant impact on patient outcomes and BMI displayed positive correlation with three-fifth of the predefined outcome measures. No significant difference was observed between repair groups; however, primary closure ± a patch achieved an MCID percentage improvement with regards to length of original stay, rate of additional admissions/surgeries and post-operative infection rate. Artificial over autologous patches resulted in shorter hospital stays, fewer readmissions, infections and neurological symptoms. Conclusion This study reports primary closure ± dural patch as the most efficient repair method with regards to the five reported outcomes. This study provides limited evidence in favour of artificial over autologous patches and recommends that dural patches be used in conjunction with primary closure. Level of evidence I Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

A Repair Method for Damage in Aluminum Alloy Structures with the Cold Spray Process

Aluminum alloy structures may be damaged due to wear or corrosion while in service. These damages will bring about huge financial costs, as well as a huge amount of energy consumption. There is an urgent need to search for an appropriate repair method in order to solve this problem. In this research, the cold spray process was used to repair the damages by using a mixture of powders with Al and Al2O3. A 7N01-T4 aluminum alloy plate with a factitious pit was regarded as the damaged sample. The microstructure, mechanical properties, and corrosion behavior were studied. The results showed that there were no visible perforative pores or cracks in the repaired areas. The microhardness of the repaired areas was in the range of 57.4–63.2 HV and was lower than that of the 7N01-T4 aluminum alloy. The tensile strength of the repaired samples was markedly improved compared with the unrepaired samples. The alternate immersion test results indicated that the repaired samples had the lowest rate of mass loss compared with 7N01-T4 and the unrepaired samples. After alternate immersion tests for 504 h, the repaired samples were covered with dense corrosion products. The repaired samples had a superior corrosion resistance compared to that of 7N01-T4. Thus, the cold spray process is a method of repairing damage in aluminum alloy structures.

Field Performance and Rapid Repair Method of an Airfield Pavement under the Blast Load of Cluster Bomb Unit

This paper discusses a field test of airfield pavement under cluster bomb unit (CBU) blast load and a study of repair method upon the examination of the damage geometry. Cluster bomb unit blast load shows a similar level to that of a typically known air-to-ground munition, and the penetration depth was calculated using empirical formulae with terminal velocity during a free fall following an explosion and dispersion 20km above the ground. Based on the calculations, the field test was executed assuming a cluster bomb unit penetration depth of 33cm for concrete pavement surface. The concrete slab on the test site was casted in a circular shape at the field and then cured. This slab was an unreinforced concrete structure with a similar compressive strength and thickness as that of airfield pavement currently in use. The test reflected the cluster munition penetration depth of 33cm, and the concrete slab was drilled in the center and explosive with a weight resembling that of the cluster munition installed. As results of the blast test show a damage to the pavement expanded the crater to a depth of 78cm, down to the crushed stone layer and with a diameter of 30cm. The concrete fragmentation requiring removal was of about 156cm in radius on average. The 7 tensile cracks across the pavement were not so heavily damaged to require removal. Cutting and removing the crushed concrete slab with dimension of 1.8m × 1.8m, compacting the disturbed crushed stone layer and repairing the concrete slab section using ultra-rapid hardening concrete are reviewed the appropriate repair method based on the above results.

Compression and Pattern Matching

We introduce our research on compressed pattern matching technology that combines data compression and pattern matching. To show the results of this work, we explain the collage system proposed by Kida et al. in 2003 that is a unifying framework for compressed pattern matching, and we explain the Repair-VF method proposed by Yoshida and Kida in 2013 and the MR-Repair method proposed by Furuya et al. in 2019 as grammar compressions suitable for compressed pattern matching.

Layer-by-Layer Repair of Small-Scale Damage of Fused Silica Based on the Magnetorheological Method

The magnetorheological (MR) repair method can effectively repair the small-scale damage of fused silica optics and further improve the laser-induced damage threshold of fused silica optics. However, at present, the rules of MR repair of small-scale damage of fused silica are not clear and cannot provide further guidance for the repair process. In this paper, the fused silica damage samples were repaired layer by layer by the MR method. The number and size changes of all the surface damage, the morphology, the fluorescence area distribution, and photothermal-absorption value of a single typical small-scale damage were measured. Through dark field scattering imaging, it is found that when the repair depth is 5 μm, the repair completion rate of damage with a transverse size less than 50 μm can reach 44%, and the repair efficiency decreases gradually with the repair process. Focusing on the whole repair process of a single typical, small-scale damage—due to the flexible shear removal mechanism of the MR method—the repair process of damage can be divided into three stages, which as a whole is a top-down, from outside to inside process. The first stage is the process of removing the surface of the damage layer by layer. In this process, MR fluid will introduce pollution to the inside of the damage. In the second stage, MR fluid begins to repair the inside of the damage. In the third stage, the MR ribbon completely covers the inside of the damage, and the repair effect is the most obvious. The measurement results of photothermal absorption and fluorescence area distribution of damage confirm this process. The photothermal absorption value and fluorescence area distribution of damage do not simply decrease with the repair process. On the contrary, they gradually increase first, and then decrease significantly when the damage depth reaches less than 1 μm. As the thickness of the MR ribbon is 1 μm, the reduction in the photothermal absorption value and fluorescence area of the damage is due to the process of repairing the inside of the damage. The results show that the absorbent impurities inside the small-scale damage of fused silica are the main factor affecting the performance. The key to repairing the small-scale damage of fused silica by the MR method is that the damaged interior must be repaired effectively. This paper outlines the MR repair method of small-scale damage of fused silica, which is of great significance to optimize the MR repair process.

Thermotechnical tests of an electronically controlled main high-speed engine of a marine vessel

Thermotechnical tests of the main engine after a malfunction for putting it back into operation under the supervision of the Register inspector are presented in the paper. The electronically controlled high-speed Caterpillar C32 engine on the port side with an output of 1000 kW is described.Experimental studies of the value influence of thermaland vibration parameters on changes in the engine technical state are carried out during thermotechnicaltests. The experimental research methodology includes a classical approach to conducting such tests and a contemporary method with remote data transmission to the office of the vessel owner’s company.The accumulated practice in conducting experimental studies of the technical condition control by the in-place repair method of diagnostics makes it possible to move from classical approaches of technical operation to new ones included in the remote control and monitoring system of vessel technical means of autonomous ships in operation.The conducted studies have shown that the obtained values of the thermal engineering and vibration parameters do not exceed the maximum permissible values specified by the manufacturer.The results of the experimental study of Caterpillar engines demonstrate the defect initiation in one of the engine mounts by exceeding the values of vibration velocity.The conducted experimental studies of vessel technical equipment by the in-place repair method of diagnostics of marine vessels in operation are the basis of the control system of autonomous ships.