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PubMed1989

The first sutureless, laser-welded, end-to-end bowel anastomosis.

The use of laser energy to weld together tissue offers great promise in the expanding field of laser surgery. The published results of laser welding intestinal tissue have, to date, been limited to the successful laser closures of small enterotomies. This is the first report of using laser energy alone to create an end-to-end small bowel anastomosis. A biocompatible, water-soluble, intraluminal stent was employed during the laser welding of this sutureless, stapleless ileal anastomosis in a rabbit model. Excellent recovery and healing were observed. The rapidity, ease, and potential for full precision automation of laser welding mandates further research.

Anastomosis, Surgical↗
PubMed1992

Changes in type I collagen following laser welding.

Selection of ideal laser parameters for tissue welding is inhibited by poor understanding of the mechanism. We investigated structural changes in collagen molecules extracted from rat tail tendon (> 90% type I collagen) after tissue welding using an 808 nm diode laser and indocyanine green dye applied to the weld site. Mobility patterns on SDS-PAGE were identical in the lasered and untreated tendon extracts with urea or acetic acid. Pepsin incubation after acetic acid extraction revealed a reduction of collagen alpha and beta bands in lasered compared with untreated specimens. Circular dichroism studies of rat tail tendon showed absence of helical structure in collagen from lasered tendon. No evidence for covalent bonding was present in laser-treated tissues. Collagen molecules are denatured by the laser wavelength and parameters used in this study. No significant amount of helical structure is regenerated on cooling. We conclude that non-covalent interactions between denatured collagen molecules may be responsible for the creation of tissue welding.

Animals↗
PubMed2003

Muscle fragment welding for control of massive presacral bleeding during rectal mobilization: a review of eight cases.

INTRODUCTION: Although massive presacral bleeding during rectal mobilization is uncommon, it can rapidly destabilize a patient. Traditional attempts at control include tamponade with pelvic packing and application of sacral thumbtacks. The aim of this review is to describe the anatomic basis of injury and summarize our experience with this challenging problem, with emphasis on the simple, readily available, effective technique of rectus abdominis muscle fragment welding. METHODS: A retrospective review of eight patients who underwent muscle fragment welding for presacral bleeding incurred during rectal mobilization was undertaken. This technique involves harvesting a small piece of rectus abdominis muscle, which is held in place with a forceps to occlude the bleeding site. Electrocautery adjusted to the highest setting is then applied to the forceps to "weld" closed the bleeding point. RESULTS: Control of presacral bleeding was achieved in all eight patients (3 males) with this technique without complications attributable to this method. Previous attempts at pelvic packing failed in all eight patients. CONCLUSION: Muscle fragment welding is a safe, readily available, and highly effective method of controlling massive presacral bleeding.

Abdominal Muscles↗
PubMed1976

Heat treatment of laser-welded gold alloys.

(1) Three alloys, G-3, SMG-2, and Ceramco-0, showed no ductility in the aswelded condition. (2) The Ney G-3 as-welded samples had no ductility, but heat treating greatly increased their yield stress. (3) The simulated ceramic firing cycle created a small amount of ductility in SMG-2, but the lowering of the yield stress in Ceramco-0 renders the welds dangerously weak even with improved ductility. (4) The Jelenko F as-welded specimens were acceptable. Heat treatment improved the joints slightly, but this is not considered necessary. (5) The Ney B-2 as-welded specimens produced satisfactory joints which did not benefit from heat treatment. The large loss in ductility with heat treatment is considered undesirable. (6) The unpredictable behavior of Ceramco-0 in this study suggests the need to evaluate each alloy individually before clinical application.

Dental Soldering↗
PubMed2000

Laser soldering and welding for ossicular reconstruction: an in vitro test.

To evaluate the possibility of laser application in ossicular reconstruction, soldering and welding of bony tissue with proteineous materials was performed by using a CO (2) laser, and the bonding strength of these materials was measured with a gradual weighing system. The soldered and welded surface of bone was observed with a scanning electron microscope. Additionally, welding of human ossicles and synthetic materials was experimentally tried with lasers, and morphologic changes were observed and recorded. A scanning electron microscopic examination was also done. A 40% albumin solution and commercial fibrin glue showed the best bonding strength. Bridging of denatured protein solder may be a mechanism of bonding. Polycel was melted by using a laser beam, and melted Polycel covered the surface of the ossicle. However, the bonding strength was not enough to use, and exact measurement of bonding strength was not possible. These results suggested the possibility of laser soldering and welding in ossicular reconstruction, especially with ossicle or cortical bone.

Animals↗
PubMed2005

Nano-welding by scanning probe microscope.

A novel method, nano-welding, analogous to spot welding at the nanoscale level using scanning probe microscopy (SPM) is presented. Using SPM oxidation of the underlying silicon, single-walled carbon nanotubes (SWNTs) have been immobilized to the surface at point sites along their lengths by the nano-welding. It is shown that this nano-welding process nearly has no structural damage to the SWNTs. This immobilization makes the SPM manipulation of SWNTs controllable and desirable, which is helpful for the construction of SWNT-based nanodevices.

Journal Article↗
PubMed2002

The influence of metallurgy on the formation of welding aerosols.

Recent research has indicated that insoluble ultrafine aerosols (ie., particles whose physical diameters are less than 100 nm) may cause adverse health effects due to their small size, and that toxicological response may be more appropriately represented by particle number or particle surface area. Unfortunately, current exposure criteria and the associated air-sampling techniques are primarily mass-based. Welding processes are high-temperature operations that generate substantial number concentrations of ultrafine aerosols. Welding aerosols are formed primarily through the nucleation of metal vapors followed by competing growth mechanisms such as coagulation and condensation. Experimental results and mathematical tools are presented to illustrate how welding metallurgy influences the chemical aspects and dynamic processes that initiate and evolve the resultant aerosol. This research suggests that a fundamental understanding of metallurgy and aerosol physics can be exploited to suppress the formation of undesirable chemical species as well as the amount of aerosol generated during a welding process.

Aerosols↗
PubMed2004

Weld characteristics of orthodontic archwire materials.

Welding attachments to archwires can produce change in their physical as well as mechanical properties. This study evaluated three archwire alloy materials-stainless steel, Beta titanium, and Timolium for their weld characteristics. The study was divided into tensile-shear test using instron universal testing machine, surface evaluation with the help of scanning electron microscope, and metallographic examination with optical microscope. Six specimens were used for evaluation of each parameter. Increased strength in tensile-shear test and smooth surface and characteristic nugget formation in scanning and optical micrographs, respectively, clearly indicated superior weld characteristics for Beta titanium alloys when compared with the other two archwire alloys. Stainless steel was found to be intermediate in nature, whereas Timolium exhibited poor weld characteristics.

Analysis of Variance↗
PubMed1999

Scanning and transmission electron microscopy study of the microstructural changes occurring in aluminium matrix composites reinforced with SiC particles during casting and welding: interface reactions

Processing of aluminium matrix composites (AMCs), especially those constituted by a reactive system such as Al-SiC, presents great difficulties which limit their potential applications. The interface reactivity between SiC and molten Al generates an aluminium carbide which degrades the composite properties. Scanning and transmission electron microscopes equipped with energy-dispersive X-ray spectroscopes are essential tools for determining the structure and chemistry of the Al-SiC interfaces in AMCs and changes occurring during casting and arc welding. In the present work, an aluminium-copper alloy (AA2014) reinforced with three different percentages of SiC particles was subjected to controlled remelting tests, at temperatures in the range 750-900 degrees C for 10 and 30 min. Arc welding tests using a tungsten intert gas with power inputs in the range 850-2000 W were also carried out. The results of these studies showed that during remelting there is preferential SiC particle consumption with formation of Al4C3 by interface reaction between the solid SiC particle and the molten aluminium matrix. The formation of Al4C3 by the same mechanism has also been detected in molten pools of arc welded composites. However, in this case there was formation of an almost continuous layer of Al4C3, which protects the particle against further consumption, and formation of aciculate aluminium carbide on the top weld. Both are formed by fusion and dissolution of the SiC in molten aluminium followed by reaction and precipitation of the Al4C3 during cooling.

Journal Article↗
PubMed1997

Investigation of laser tissue welding dynamics via experiment and modeling.

An in vitro study of laser tissue welding mediated with a dye-enhanced protein solder was performed. Freshly harvested sections of porcine aorta were used for the experiments. Arteriotomies approximately 4 mm in length were treated using an 805 nm continuous-wave diode laser coupled to a 1-mm diameter fiber. Temperature histories of the surface of the weld site were obtained using a fiberoptic-based infrared thermometer. The experimental effort was complemented by the LATIS (LAser-TISsue) computer code, which numerically simulates the exposure of tissue to near-infrared radiation using coupled Monte Carlo, thermal transport, and mass transport models. Comparison of the experimental and simulated thermal results shows that the inclusion of water transport and evaporative losses in the model is necessary to determine the thermal distributions and hydration state in the tissue. The hydration state of the weld site was correlated with the acute weld strength.

Animals↗
PubMed1995

Laser welding versus suturing in tunica vaginalis and venous patch graft corporoplasty.

Congenital penile curvature may result from corporeal disproportion in nearly 40% of cases, while in adults scarring of the corporeal bodies or periurethral fibrosis accounts for the majority of cases. Some surgeons advocate lengthening the fibrosed corporeal bodies by excising tunica albuginea and grafting such defects to straighten the penis. Tunica vaginalis, dermis, dorsal vein and lyophilized dura have been used for this purpose. Traditionally, these graft biomaterials have been sutured to the tunica albuginea. We assessed the feasibility, short-term safety and efficacy of diode laser tissue welding using albumin based solder and indocyanine green dye to perform patch graft corporoplasty in the dog. Ten animals were subjected to bilateral transverse excision of 1 x 2 cm. sections of tunica albuginea. Corporoplasty was performed using grafts composed of saphenous vein (5) or tunica vaginalis (5). Microsurgical repair with 7-zero polydioxanone suture (10) was compared to contralateral laser welded repair (10) by recording operative time, initial and short-term bursting pressures (mean plus or minus standard deviation) and histological analysis. Operative time on the laser side (9.8 +/- 2.3 minutes) was significantly shorter (p < 0.05) than on the suture side (17.1 +/- 5.1 minutes). Leak pressures, initially (laser 105.7 +/- 23.8 mm. Hg versus suture 35.3 +/- 8.0 mm. Hg), at 3 to 5 days (greater than 333.3 +/- 62.4 mm. Hg versus 136.6 +/- 39.4 mm. Hg) and at 7 to 10 days (greater than 397.8 +/- 39.8 mm. Hg versus 191.5 +/- 46.4 mm. Hg) were higher (p < 0.05) in the laser side compared to controls. Graft failure (necrosis) occurred in 3 repairs (2 laser on day 4 and 1 suture on day 10). Viable tissue with minimal differences in foreign body reaction between groups was observed in the remaining grafts. We conclude that laser welded patch graft corporoplasty using tunica vaginalis or vein is easy to perform, and provides excellent initial and short-term leak pressures. The use of laser welding in conjunction with suturing may be beneficial in corporoplasty for congenital or acquired penile curvature.

Animals↗
PubMed1994

Surgical diathermy is not suitable for vascular tissue welding.

The possibility of using radiofrequency energy (RFE) to produce a sutureless anastomosis is attractive both to the military surgeon and on the grounds of cost and simplicity. To investigate this, fresh rabbit aorta was divided lengthways into 4 mm strips and apposed, intima-to-itima. A Valleylab Force 30 Electrosurgery machine supplied RFE at 500 kHz. The energy was applied using standard bipolar forceps and 121 attempts were made to weld the tissue. Seventy seven welds resulted of which 36 were able to withstand a distraction force of greater than 0.1N: the strongest weld was disrupted at 0.35N. Intact tissue withstood a distraction force of greater than 2N, whilst sutured joints disrupted at 0.97 N. It is concluded therefore that radiofrequency energy at 500 kHz does not satisfactorily weld vascular tissue.

Anastomosis, Surgical↗
PubMed1990

Potential of radio-frequency balloon angioplasty: weld strengths, dose-response relationship, and correlative histology.

Previous studies have established the feasibility of combining tissue heat generated by radio-frequency (RF) current and mechanical pressure to manage problems of percutaneous transluminal angioplasty (PTA) that are thought to cause postangioplasty restenosis (PARS). In the current in vitro study of normal and atherosclerotic human aortic layers (intima-media and media-adventitia) separated artificially, the purposes were to identify a dose-response relationship between the total RF energy delivered and the resultant weld strength between vascular tissues and to study the histologic correlates. Twenty-eight control and 100 experimental specimens were evaluated. The mean weld strength for all specimens with no RF current (at 0 J) was 4.1 g +/- 2.0; at 100 J, 5.9 g +/- 2.8; at 200 J, 28.5 g +/- 3.3; at 300 J, 50.0 g +/- 5.5; and at 500 J, 82.0 g +/- 8.2. Inspection of treated specimens revealed vascular molding (depression in the surface corresponding in dimensions to those of the electrode gap in the treatment chamber). Histologic examination revealed necrosis in the region underlying the electrode gap, a hypocellular fusion zone, indistinct boundaries between welded specimen parts, and transition zones to normal histologic characteristics at either end of each specimen. RF energy combined with mechanical pressure produces dose-dependent thermal welds in artificially dissected vascular tissues, molding of vascular tissue, and cellular destruction in the media. These findings may have clinical application in the management or prevention of all forms of PARS in humans and in the treatment of spontaneous aortic dissection.

Angioplasty, Balloon↗
PubMed2006

Accuracy of temporary laser welding of FPDs by Nd:YAG laser in the oral cavity.

The purpose of this study was to investigate the accuracy of temporary fixation with laser welding for fixed partial dentures (FPDs). Five kinds of experimental FPD with different welding/soldering gaps were fabricated (0, 20, 50 microm for welding; 300 microm for soldering). Then, FPDs were temporary-fixed by laser welding or with a self-curing resin. Fixation accuracy was evaluated by the change in distance and the angular deformation between two retainers. The change in distance and the angular deformation between two retainers of the FPD without welding/soldering gap were significantly larger than the other FPDs (p<0.05). With due consideration to the displacement of teeth or implants especially in the mesiodistal direction, and by taking into account the inevitable errors of the indirect method, it seemed reasonable to provide a welding space of approximately 20 microm.

Dental Prosthesis Repair↗
PubMed2000

[Comparative study of technique of laser welding ceramo-alloy by different gap distance].

OBJECTIVE: To investigate the quality of laser welded non-precious base alloy by different gap distance and its clinic probability. METHODS: Laser welded ceramo-alloy CW-PA specimens by different gap distance of 0.0 mm, 0.25 mm, 0.5 mm, Tested joined sample's UTS, microhardness; took SEM examination on its tensile fracture surface and metallographic examination on longitudinal cross section. RESULTS: The study showed that UTS of Laser welded CW-PA by different gap distance of 0.0 mm, 0.25 mm, 0.5 mm is (446.05 +/- 82.50) MPa, (485.97 +/- 62.35) Mpa, (503.32 +/- 65.79) MPa respectively, approach to original rod (421.53 +/- 21.78) MPa (P > 0.05). Microimage at tested samples of gap distance at 0.0 mm, 0.25 mm are good. CONCLUSION: It revealed that 1. Laser welding specimen should be contacted as close as possible 2. The gap distance should be less than 0.5 mm, 0.25 mm is better, and easy to handle.

Dental Soldering↗
PubMed2004

[Effect of irradiation power on the mechanical properties of laser-welded titanium joints.].

PURPOSE: To make an clinical implication for the use of laser welding pure titanium,this study investigate the effect of irradiation power on the mechanical properties of laser-welded joints. METHODS: The pure titanium tensile test and three-point bending test rods were laser-welded with different irradiation power. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis was also performed on polished longitudinal sectioned samples. RESULTS: A small portion of the central area in group 1.4 kW was not joined. ANOVA showed no significant difference of OTS and VBS between group 1.6 kW and group 1.8 kW at the 0.05 level. SEM examination and metallurgical analysis showed that there were defects such as pores and cracks in the welding zone; and as the irradiation power increased, there were more pores and cracks. CONCLUSION: The increase in laser irradiation power cannot increase melting depth significantly.

Dental Soldering↗
PubMed2004

[Effect of laser irradiation power on the mechanical properties of Co-Cr and Ni-Cr laser-welded joints.].

PURPOSE: To investigate the effect of different irradiation power on the mechanical properties of laser-welded joints. METHODS: The standard tensile test and three-point bending test rods made from Co-Cr and Ni-Cr alloy were laser-welded with different irradiation powers. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis and microhardness test were also performed on polished longitudinal sectioned samples. RESULTS: For Co-Cr alloy, greater irradiation power resulted in greater UTS, minor UBS. For Ni-Cr alloy, there was no significant difference of UTS and UBS between the four groups. SEM and metallurgical examination showed that the welded zone exhibited more gas pores and cracks as the irradiation power increased. Microhardness test showed that hardness increased toward the center of the welded zone and as the irradiation power increased, the range of hardness increased was expanded. CONCLUSION: The optimal laser irradiation power was the key to achieved superior mechanical properties joints.

Chromium Alloys↗
PubMed2005

[The plasm welding of the digestive system organs in experiment].

The plasm welding of the gut organs--perspective trend, which permits to increase the surgeon possibilities in performance of operative intervention. The results of operations, performed on large intestine and stomach, trusts, that it is possible to apply the streams of the high temperature gas plasm for the tissues dissection and connection. There are such advantages of the method, as the operation time shortage, simplicity in manipulating "Plasmomed" apparatus, absence of foreign bodies in the connection zone, high degree of hemostasis achieved. After the operation there was observed rapid restoration of the main structure elements in the large intestine and stomach wall, localized in the plasm welding zone. There was elaborated and tested a new method of the living tissues welding, and the processes, occurring in tissues within the plasm welding application zone, were studied up.

Animals↗