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PubMed1992

Health evaluation of an aerosol formed in the fumes from mild steel welding electrodes.

Welding is one of the processes which cause multivarious problems to health. It requires considerable attention because of its severe hazards. During welding very harmful fumes and heat are emitted which have adverse effects on the health of the welder and people working in his vicinity. In the present work microfibre glass filter paper (GF/A) was found to be the preferable media for sampling of the fumes from mild steel electric welding electrodes for the evaluation of the trace elemental composition of the fumes. Using neutron activation analysis considerable amounts of the most harmful elements such as Ba, Co, Cr, Sb, Rb, Sc, As and Fe were observed.

Aerosols↗
PubMed2004

Potential oxidative stress in the bodies of electric arc welding operators: effect of photochemical smog.

OBJECTIVE: To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. METHODS: Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. RESULTS: Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P < 0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P < 0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P < 0.05-0.005), the value of LPO in the WOs was increased gradually (P < 0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P < 0.005-0.001), but LPO increased (P < 0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients' alpha (6 items) was 0.8021, P < 0.0001, and that the standardized item alpha was 0.9577, P < 0.0001. CONCLUSION: Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.

Adult↗
PubMedDate not supplied

Laser welding and irradiation in alcohol preserved homografts.

This experiment examined the effect of laser welding and irradiation on the patency rate of microvascular anastomoses done with alcohol preserved homografts. The carotid arteries from Sprague-Dawley rats were freshly harvested and preserved in 70% ethyl alcohol for at least 3 weeks. The homografts were interposed into the carotid arteries with one of the following techniques: Group I, grafts were anastomosed with three stay sutures and laser welding (carbon dioxide laser, 90 mW); Group II, anastomoses were completed with eight to nine interrupted sutures (10-0 nylon); or Group III, the same technique used in Group II, but followed by laser irradiation (90 mW for 1 min) of the grafts. These results showed that patency at 2 weeks was 73% in Group I, 71% in Group II, and 82% in Group III, respectively. The patency at 12 weeks was 67% in Group I and unchanged in Groups II and III. In conclusion, laser irradiation and laser welding did not increase the patency rate of microvascular anastomoses done with alcohol preserved homografts. Thrombotic occlusion in microvascular homografts usually occurs before the second week postoperatively.

Anastomosis, Surgical↗
PubMed1990

[Removable partial dentures applied by electric welding and soldering methods].

The joining procedure for uniting metal structures is very important in the dental clinic, and various kinds of metal joining methods have been performed for clinical application. The conventional torch soldering method using a blow torch has been generally adopted. However, it has several clinical problems, especially in the construction of removable partial dentures. The base metal wires made of a chromium-cobalt alloy are subject to changes in their mechanical properties caused by heating, when wrought wire clasps are joined to rests or frameworks. In addition to the flexibility of wrought wire clasps, damage to acrylic resin denture bases and acrylic resin teeth occurs in the repair of removable partial dentures. In this paper, the electric resistance welding and soldering methods were applied to attach wrought wire components to a removable partial denture framework to resolve the problems of the torch soldering method. As a result, it is suggested that these electric resistance welding and soldering methods have the following advantages, as compared with the conventional torch soldering method. 1. When using this electric resistance welding method, it is possible to fix metals temporarily to each other more securely and strongly than the conventional temporary fixation methods using sticky wax or acrylic resin. 2. The electric resistance soldering method does not require any heat insulation or a partition as the torch soldering method does, because the soldered area is only heated partially. 3. In the case of soldering electrically wrought wire clasps to metal structures such as rests and connectors, there is no fear of of overheating a wide area of wires.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromium Alloys↗
PubMed1991

[Current status of the control of the levels of harmful substances in the air of the work area during welding].

The article reveals the current issues pertaining to the improvement of control after hazardous substances contents in the welding working zone air. The welding aerosols are multicomponent and constitute a group of complex gas-aerosol mixtures,--the feature which requires a separate detection of the individual concentrations of the most hazardous components, both hard and gaseous. Data on the specific excretion of hazardous substances should be included in respective technical documentation relating to welding processes and materials.

Air Pollutants, Occupational↗
PubMed1978

[Tear resistance of laser-welded dental alloys].

The investigation was undertaken to establish the place of lasers as tools in the dental technical laboratory. Tests were undertaken to study resistance to tears in laser welded dental metal alloys. (Degudent U, Degulor M of Fa. Degussa.) Availabel as laser apparatus were a cw Nd:YAG-laser (400 Watt capacity) and a pulse Nd:YAG-laser (max. 45 pulse energy, 9.2 pulse length). Welding tests on models with both lasers resulted in higher resistance to tears than was achievable by conventional soldering processes. Furthermore it could be shown that in certain alloy compositions, used in our experiments, welding by the cw process resulted in greater resistance to fissuring than by the pulse process. By adopting the alloy as well as the preparation of appliances to the laser process we feel that markedly superior results can be achieved as we describe in this first communication.

Dental Alloys↗
PubMed1988

[Methodology and evaluation of exposure to fumes formed during welding of chromium-nickel steel].

Using various methods for determination of welding fumes components and taking into account a simultaneous determination of soluble compounds of chromium III and IV, hygienic evaluation in two working places employing different systems of MMA/SS welding, TIG/SS welding and padding was carried out. As it is indicated by the results, proper hygienic evaluation of working conditions is possible owing to the measurements of individual exposure of workers in the breathing zone, allowing for determination of chromium manganese, nickel, and, while applying low-hydrogen electrodes, also fluorides, in every test.

Air Pollutants, Occupational↗
PubMed1984

Nickel in welding fumes--a cancer hazard to welders? A review of epidemiological studies on cancer in welders.

Although the high exposures to metallic aerosols that were formerly encountered in the primary nickel industry are no longer prevalent, large occupational groups, such as welders, are currently exposed to moderate levels and may therefore be at some degree of health risk. Examination of the world literature reveals a number of epidemiological studies which demonstrate a slight excess risk of respiratory tract cancer incidence among the general welding population. Several of these studies are suggestive of the possibility that there may be a larger excess risk exclusively limited to those welding cohorts who are exposed to nickel and chromium in the fumes from the welding of stainless and high alloy steels. Such a hypothesis, although supported in part by in vitro and in vivo genotoxicity tests, can only be verified by international collaboration in specifically designed epidemiological studies using a uniform protocol.

Adult↗
PubMed1995

[Comprehensive evaluation of protective measures in electric welding].

Protective effects of safety masks, eyewear, work clothes, gloves, periodically physical examination system, and ventilation and barriers at workplace, were evaluated by one-way analysis for handtorch welding, carbon dioxide gas-protective welding, and argon-arc welding operations, etc. in township and village enterprises and state-owned enterprises by interviewing managers in the departments of technology and work safety and field investigating. Based on the results of one-way analysis of protective measures, comprehensive evaluations of various enterprises were made with a fussy mathematical model. Both enterprises in township and village level and of state-owned were graded as A on a basis of the evaluation, which will be helpful to the better management of occupational health in the future.

Evaluation Studies as Topic↗
PubMed1977

Welding light.

Two types of electric welding, welding with gas-shielded arcs and welding with coated electrodes, are considered in this paper. The possible radiation injuries to the eye are described, and the measures for protection discussed.

Eye Injuries↗
PubMed1996

Occupational asthma from welding: a case report.

Occupational asthma is one of the commonest occupational lung diseases. This is a case of asthma related to arc-welding in a shipyard. Serial peak expiratory flow rate readings were taken with and without exposure to the welding process. The results showed that the patient had occupational asthma from welding. This case report serves to remind us of the need to ask every adult with asthma for their occupational history. It emphasises the need for early diagnosis and removal from the cause of asthma. A delay in diagnosis may lead to non-specific bronchial reactivity and persistence of symptoms.

Adult↗
PubMed1998

Repair strength dependence on solder protein concentration: a study in laser tissue-welding.

BACKGROUND AND OBJECTIVE: A novel laser-activated solid solder has been coupled with a diode laser to investigate the dependence of the solder protein concentration on the tensile strength of the soldered tissues. The uncertainty of laser welding, due to the fluid glue, was overcome using the solid solder. STUDY DESIGN/MATERIALS AND METHODS: Sixty-two severed rat tibial nerves and vas deferens were repaired using rectangular protein bands with two different albumin concentrations (58% and 68% by weight). The laser power (90 mW and 140 mW), dose (12.9 +/- 0.7 J/mg, mean +/- s.d.), and solder dimensions (thickness = 0.15 +/- 0.01 mm, surface area = 7.8 +/- 0.4 mm2) were kept constant during the operations. RESULTS: The laser welds with high protein solder concentration were significantly (P < 0.05) stronger (28 +/- 3.5 g) than the welds with low protein solder concentration (23 +/- 5 g). CONCLUSIONS: The average tensile strength of the laser soldered tissues increased as the protein solder concentration increased.

Animals↗
PubMed1999

Laser welding for vascular anastomosis using albumin solder: an approach for MID-CAB.

BACKGROUND AND OBJECTIVES: To improve minimally invasive direct coronary artery bypass surgery (MID-CAB), new techniques of vascular anastomosis that are faster and more reliable need to be developed. STUDY DESIGN/MATERIALS AND METHODS: Common carotids in a canine model were transected and an end-to-end anastomosis was performed by using one of four techniques (1) continuous 6-0 polypropylene closure (suture; n=6), (2) vascular clip (VCS; n=6), laser welding using 50% albumin solder with (3) a 1.32-micro laser (1.32las; n=6), and (4) a 1.9-micro diode laser (1.9las; n=4). Times for anastomosis (TA) were compared between groups by t-test. Pressures at which anastomosis failed (leak point pressure, LPP) were determined and compared by analysis of variance. RESULTS: TA was faster for 1.32las and 1.9las at 8.4+/-0.7 and 7.8+/-0.3 min, respectively, when compared with suture at 13.8+/-1.0 min (P=0.001, confidence interval [CI]-8.1, -2.6 for 1.32las and CI -8.9, -3.1 for 1.9las). There was no statistical difference between VCS (8.3+/-3.3 min) and any other group (P > 0.17). LPPs (mm Hg) were similar for all groups: 350+/-37 for 1.32las, 280+/-31 for 1.9las, 347+/-46 for suture, and 358+/-53 for VCS, P=0.68. CONCLUSIONS: In this study, laser welding using 50% human albumin solder resulted in faster anastomotic times. Anastomoses were equivalent to conventional sutured anastomoses in failing at similar pressures. Laser welding using human albumin solder may be advantageous in improving coronary anastomoses during MID-CAB, but long-term anastomotic strength and histologic evaluation need to be investigated.

Adhesives↗
PubMed2000

Morphometric and functional results after CO(2) laser welding of nerve coaptations.

BACKGROUND AND OBJECTIVE: Several reports describe nerve coaptations by laser welding in combination with stay sutures and bonding material. This study was undertaken to obtain functional and morphologic information by using a nerve coaptation technique by epineurial CO(2) laser welding only. STUDY DESIGN/MATERIALS AND METHODS: The sciatic nerves of 24 rats were transected and epineurially coapted with the CO(2) laser at 60 mW or with microsutures as a control. Walking track analysis were carried out to evaluate the functional recovery, and the nerves were harvested for histology after 6 months of regeneration. RESULTS: None of the 24 nerves showed dehiscence of the coaptations, and all showed good nerve fiber regeneration. Better results were obtained for the functional evaluation of the sciatic function index (P < 0.02) and the toe spread index (P < 0.04) from the laser nerve coaptations. Likewise, the morphologic evaluations of the fiber density (P < 0.04) and area fraction (P < 0.002) were better in the laser group. CONCLUSION: CO(2) laser welded nerve coaptations are as successful as their sutured counterparts and may become a promising alternative in clinical practice.

Animals↗
PubMed2001

Comparison of argon-laser welded and sutured repair of inferior vena cava in a canine model.

BACKGROUND AND OBJECTIVE: Advantages of laser-welded microarterial anastomoses have been reported. However, whether laser repair of large veins is advantageous is not yet known. Argon-laser welding of inferior vena cava was therefore compared with conventional-sutured repair. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four adult mongrel dogs were used. Twelve inferior vena cavas were repaired using an argon laser and the rest using continuous sutures. Specimens were removed at 2, 8, 16, and 24 weeks after repair. Technical characteristics, cavographical findings, and results of histopathological study using light and transmission electron microscopy were compared. RESULTS: Procedure time did not significantly differ between the two groups. The sutured repair sites were narrower than those repaired by laser immediately after and at 2 and 24 weeks. Histologically, laser welding resulted from denaturation of collagen and mild healing occurred simultaneously with the disappearance of denatured collagen. By contrast, there was strong fibrotic reaction at sutured repair sites. CONCLUSIONS: These findings suggest that argon-laser repair of large veins is superior to continuous suturing.

Anastomosis, Surgical↗
PubMed1988

Laser balloon angioplasty: effect of constant temperature versus constant power on tissue weld strength.

Thermal fusion of intimal plaque with the arterial wall during coronary balloon angioplasty may significantly reduce the incidence of abrupt closure and may reduce the occurrence of delayed restenosis by improvement of luminal size and shape. Although Nd:YAG laser energy has been shown to be effective in the thermal fusion of plaque-arterial wall separations in vitro, the most efficient manner of energy delivery for rapid achievement of therapeutically useful equilibrium tissue temperature during laser exposure has not been defined. A comparison of weld strength achieved was therefore made between two formats of laser delivery: constant power vs. decremental power with an initial high dose followed by the minimal serial decrements necessary to maintain tissue temperature constant for 15 seconds. One hundred sixty-six tissue discs of human postmortem aorta of 11 mm diameter were studied. Intimal plaque was separated from the media, the two layers were juxtaposed, a force of 4 pounds was applied, and a fiberoptic-delivered laser beam was directed perpendicular to the tissue over a 3-mm-diameter nominal spot size. Weld strength was measured as the shear force required to separate completely the two tissue layers. The mean weld strength (75 g) achieved by use of the decremental power format was significantly higher (P less than .01) than the mean strength (32 g and 56 g) achieved by using constant power for 20 and 30 seconds, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1994

Healing process of laser-welded intestinal anastomosis.

Intestinal welding by means of low-power laser has been reported as an efficient method for intestinal anastomosis. We designed an experimental model in rats to investigate collagen and DNA concentrations in CO2 laser-welded anastomoses as compared with those in sutured anastomoses on the 4th, 7th, and 10th postoperative days. The results revealed that DNA, total collagen, and insoluble collagen concentrations were significantly lower in the lased anastomoses than in the sutured anastomoses on the 4th postanastomotic day. On the 7th and 10th postanastomotic days, collagen concentrations increased in the laser-treated group attaining significantly higher levels than in the sutured group at that time. These findings are compatible with other studies demonstrating that laser-welded intestinal anastomoses are more prone to dehiscence during the first 4 postanastomotic days, but become at least as effective as the sutured ones with passage of time.

Anastomosis, Surgical↗
PubMed1994

Silver halide fiber optic radiometric temperature measurement and control of CO2 laser-irradiated tissues and application to tissue welding.

Tissue heating by laser irradiation has attained importance in many clinical applications. Accurate temperature measurements of laser-irradiated tissues are difficult to achieve, and experiments have produced conflicting results. Fiber optic radiometry allows temperature measurement of laser-irradiated tissues by remote sensing of the emitted infra red (IR) radiation. We have developed an IR fiber optic radiometer capable of accurate tissue temperature measurements (+/- 0.2 degrees C) and utilized it to monitor and control the heating of tissues by CO2 laser irradiation. Tissue temperature control of +/- 2.5 degrees C was achieved. This system was used to control tissue temperature during CO2 laser-assisted welding of urinary bladders in rats. The strength of the welds was recorded for different welding temperatures. A temperature of 55 degrees C was found to be optimal.

Animals↗