Sutureless bowel anastomosis using Nd:YAG laser

Small bowel anastomoses were performed without sutures by using the Nd:YAG laser to produce welded enterotomies. Optimal energy levels for contact and noncontact laser were determined. Anastomoses produced using five target energy levels between 100 and 500 J were examined. Short-term anastomotic strength of these enterotomies was measured 1 min after the welding. Bursting pressure of the laser welded enterotomies was compared to the bursting pressure of traditional two-layer, inverting, interrupted sutured bowel anastomoses. The overall mean bursting pressure of non-contact-welded enterotomies was 50.6 mmHg. Optimal laser settings determined in this initial phase were then used to produce anastomoses in rabbits which are recovered postoperatively for 1 or 2 weeks in order to examine long-term viability and integrity of the anastomoses. All chronic rabbit preparations recovered without complication. The mean bursting pressure was 200 mmHg, not significantly different from that of uncut bowel or two-layer sutured anastomosis.     

Progressive motor syndrome in a welder with pallidal T1 hyperintensity on MRI: A two-year follow-up.

Chronic exposure to manganese (Mn) fume during welding may lead to mainly extrapyramidal syndrome that is resistant to treatment. We present a 32-year-old patient who developed severe postural instability, Parkinsonism, dystonia, and pyramidal signs in the 10th year of welding. The neurological condition of the patient worsened markedly in the following 3 years, resulting in severe disability rendering him to be assisted in all his daily activities and he did not benefit from any dopaminergic agent. T1 sequences of the MRI of the brain showed pallidal hyperintensity symmetrically. Welders in our country often protect their eyes but ignore to use tools that protect them from inhalation of the fume. Since chronic Mn toxicity may cause serious disability and irreversible neurological disturbances, we strongly believe that it is necessary to inform welders and their employers about this potential hazard.     

Occupational chronic exposure to metals

Summary Stainless steel welders (n = 103) were examined. To estimate external exposure, personal air sampling was used. Internal exposure was quantified by the determination of nickel levels in erythrocytes, plasma and urine. Men and women (n = 123) were examined for control purposes. In the plasma and erythrocytes of the controls the nickel concentration was below the level of detection (< 1.81 μg/l). The element concentrations in urine were between < 0.1 and 13.3 μg/l. Of the controls 95% showed nickel levels in urine below 2.2 μg/l (reference value). The average concentration of nickel in the air was 93 ± 81 μg/m³. The average concentration of nickel in the plasma samples was 4.9 ± 4.0 μg/l (95th percentile 12.8 μg/L). In erythrocytes nickel could not be detected. The nickel concentrations in the urine of the welders were 18.5 ± 28.5 μg/l on average (95th percentile 52.5 μg/l). Only a weak correlation between the nickel levels of plasma and urine could be detected (C_urine = 2.07 + 8.45 C_plasma; r = 0.294; p < 0.01). Based on our results and on the reported literature a future limit value for the nickel concentration in urine should lay between 30 and 50 μg/l. This value corresponds to an external exposure of 500 μg nickel per cubic metre.     

Exposure to soluble barium compounds: an interventional study in arc welders

Summary Soluble barium (Ba) compounds are well-known toxicants. Intoxications are mainly known in an acute form from casual or suicidal oral ingestion. No scientifically based data are available on possible health effects of inhalative exposure to soluble Ba salts at the workplace. Therefore, we investigated 18 welders in an interventional study over 1 week. They performed welding of Ba-containing stick electrodes and self-shielded flux cored wires under conditions similar to real working conditions. The welding fumes contained 31%–37% Ba, more than 90% of which was soluble in acids. Without appropriate preventive measures, a high rate of measurements exceeded the TLV values for total welding fumes of 5 mg/m³ and for soluble Ba of 0.5 mg/m³. The median fume concentrations were 13.2 mg/m³ in stick electrode welding and 12.3 mg/m³ in flux cored wire welding. The median Ba concentrations were 4.4 and 2.0 mg/m³ respectively. An integrated exhaust system built into the gun proved to be efficient in flux cored wire welding. The internal exposure to Ba reached median urine levels up to 101.7 g/l (normal: below 20 g/l) and median plasma concentrations of up to 24.7 g/l (normal: below 8 g/l). No health impact on the welders could be proven, but hypokalemia may have occurred as a result of the Ba exposure.     

用金属磁记忆方法进行缺陷检测

介绍了金属磁记忆检测的原理及其应用方法。铁磁性工件在载荷的作用下,应力和变形集中区会产生最大的漏磁场变化,对漏磁场法向分量的测定可以准确地推断工件的应力集中区。通过对14块对接焊缝钢板分别用磁记忆、超声波方法进行实际检测,验证了磁记忆检测方法的有效性,取得了一些有益的经验。     

Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy

Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.     

Maculopatía fótica: revisión de la literatura (ii)

The human retina, as transducer of light energy, is especially exposed to light toxicity. Solar maculopathy has been the only form of photic maculopathy for millennia, often secondary to the observation of an eclipse. During the last century, technological advances have led to the appearance of new forms of photic maculopathy, related to the exposure to new forms of artificial light, such as welding devices and lasers. In recent years the general use of laser pointers has led to an upturn in interest in this pathology. The aim of this review is to offer an integrated view of the different types of photic maculopathy. Due to the extension of the topic, the review is presented divided into 2 parts. In this second part, atomic bomb maculopathy, laser maculopathy, iatrogenic forms of photic maculopathy, and foveomacular retinitis are presented.     

Tissue anastomosis using a KTP laser: An experimental study

Summary

Sutured visceral anastomoses are time-consuming and complex when performed endoscopically. Theoretically, laser-welded visceral anastomoses are possible and are potentially easier and quicker to perform endoscopically than the sutured anastomoses. In this living canine study, we compared the operating time and intraluminal bursting pressure of laser-welded vs sutured anastomoses of (1) common bile duct (CBD), (2) small intestine, (3) colon and (4) ureter. Each organ was joined to itself using both anastomotic techniques. Welded anastomoses were much quicker in each organ system. Watertight anastomoses were achieved in each organ tested with both anastomotic techniques. Intraluminal hydrostatic bursting pressures occurred at lower pressures (approximately 70% of sutured anastomosis bursting pressure) in all organs. Though not qualified, tensile disruption pressure appeared to be significantly lower in the welded anastomoses as compared to the sutured anastomoses. Laser-welded visceral anastomoses are rapid and watertight. Compared to sutured anastomoses, welded anastomoses are less secure to intraluminal bursting pressures and probably less to tensile pressures. Strength enhancing adjunctive measures, such as serosal adhesives or serosal clips, may strengthen welded anastomoses and are worthy of additional studies.