Stainless Steel Clamp Research Articles

Evaluation of the forces applied by rubber dam clamps on mandibular first molar teeth with different endodontic access cavities: a 3D FEA study.

This study aimed to examine the effect of the force applied by rubber dam clamps made from different materials on mandibular first molar teeth with various designs of endodontic access cavities using finite element analysis. A intact tooth (IT) and seven different endodontic access cavities namely, a traditional endodontic cavity (TRADAC), a guided endodontic cavity (GEC), a conservative endodontic cavity (CAC), an ultra-conservative access cavity (UAC), a truss access endodontic cavity (TRSAC), a mesial caries access cavity (MCAC), and a distal caries access cavity (DCAC), along with two different clamp finite element models, were created. The clamp models were made of polyether ether ketone (PEEK) and stainless steel (SS). The forces applied by the clamps were calculated based on the axial section distance of the tooth, and these forces were applied to the contact areas on the tooth. Stress distribution models were calculated using maximum von Mises (vM) stress. The lowest vM stress under the forces applied by the SS and PEEK clamps was found in the IT model (80.914 MPa) with the PEEK clamp. The highest vM stress was found in the DCAC model (759.49 MPa) applied with the SS clamp. The forces applied by SS clamps resulted in higher vM stress values in every cavity design than those applied by PEEK clamps. PEEK clamps generated less force than SS clamps. However, clinicians should follow various isolation strategies (clamp made of different materials, split dam, etc.) according to different cavity types of the tooth.

Evaluation of the effect of different rubber dam clamps on the mandibular first molar with Finite element analysis

The aim of this study was to evaluate the stress induced by clamps made of different materials on mandibular first molar teeth using finite element analysis. The tooth model to be used in the study was created using micro-CT scanner and the rubber dam clamp model was created in three dimensions (3D) using Solidworks and applied to a finite element tooth model of an intact mandibular first molar. The size of the clamp opening and the force to be applied were calculated according to the buccolingual distances of the tooth. The contact areas of the clamps on the tooth were determined and subjected to force. The stress distribution patterns and maximum von Mises stresses were calculated and compared against these forces. The most stress against these forces occurred in the enamel tissue on the distal side where the clamp was in contact with the tooth. The stress value in the stainless steel clamp (191.63 MPa) was approximately 85% higher than the clamp made of polyethylene ketone (103.85 MPa). The stress in the dentin and pulp tissue of the tooth was negligible. Clinicians should examine the enamel tissue below the equatorial line of the tooth in detail before clamp application. The forces exerted by stainless steel clamps can cause damage to the enamel tissue of the tooth or progression of an existing enamel crack.

Research on the Vibration Characteristics of Aviation Hydraulic Clamp and Pipeline Based on Hard Coating

Aviation hydraulic clamp-piping systems often experience damage due to vibration, which poses a great threat to the reliability and safety of the aircraft. In this paper, a hard coating is used as a new damping method to study the vibration characteristics of aviation hydraulic clamp-piping systems. Three kinds of coated clamp entities are obtained by optimization and preparation, and the combination of finite element simulation and experiment is used to analyze the vibration response of the high- and low-pressure rotor under fixed-frequency simple harmonic excitation, and the resonance response under sweep-frequency excitation of the aviation hydraulic clamp-piping system. Through orthogonal experiments, it is clear that 304 stainless steel clamps coated with 200-μm-thick YSZ-PTFE coating have the best vibration damping effect on the clamp-piping system; that is, the damping rate can reach 24.67% under fixed-frequency excitation, and swept frequency damping can reach 19.93%. The maximum error between the simulation and the experimental vibration response amplitude is 7.9%, which proves the correctness of the model and verifies that the YSZ-PTFE hard coating can significantly improve the vibration damping effect with very good application prospects.

Experimental Study on Microwave-Based Curing Process with Thermal Expansion Pressure of PTFE for Manufacturing Carbon Fiber/Epoxy Composites.

Conventional composite curing incur high production costs because of their long processing times. In contrast, microwave curing process (MCP) can reduce the production costs because both the mold and the composite parts can be heated directly. In this study, a mold consisting of polytetrafluoroethylene (PTFE), quartz glass, and stainless steel clamps was manufactured to cure composite specimens of carbon fiber and epoxy resin. Flame test was conducted prior to the MCP to confirm whether the spark occurred in the mold and the composite prepreg. Uniaxial tensile tests and three-point bending tests were then conducted to obtain the mechanical properties of the composite specimens according to the input power and the processing time. The mechanical properties of the composite specimens fabricated by MCP were compared with those of composite specimens manufactured by PCF. The results show that MCP can cure the composite prepreg more rapidly than PCF and can attain comparable mechanical properties.

Evaluation of the Fretting Resistance of the High Voltage Insulation on the ITER Magnet Feeder Busbars

The high voltage (HV) insulation on the ITER magnet feeder superconducting busbars and current leads will be prepared from S-glass fabric, pre-impregnated with an epoxy resin, which is interleaved with polyimide film and wrapped onto the components and cured during feeder manufacture. The insulation architecture consists of nine half-lapped layers of glass/Kapton, which is then enveloped in a ground-screen, and two further half-lapped layers of glass pre-preg for mechanical protection. The integrity of the HV insulation is critical in order to inhibit electrical arcs within the feeders. The insulation over the entire length of the HV components (bus bar, current leads and joints) must provide a level of voltage isolation of 30 kV. In operation, the insulation on ITER busbars will be subjected to high mechanical loads, arising from Lorentz forces, and in addition will be subjected to fretting erosion against stainless steel clamps, as the pulsed nature of some magnets results in longitudinal movement of the busbar. This work was aimed at assessing the wear on, and the changes in, the electrical properties of the insulation when subjected to typical ITER operating conditions. High voltage tests demonstrated that the electrical isolation of the insulation was intact after the fretting test.

Transgranular stress corrosion cracking of 304L stainless steel pipe clamps in direct use geothermal water heating applications

Direct use geothermal heating relies on heat extracted from naturally occurring geothermal water sources to provide heating needs for commercial and residential use. The city of Boise, Idaho maintains the largest district geothermal heating system in the United States, utilizing a source of geothermal water at 80°C. 304 Stainless steel (UNS S30400) pipe clamps are used throughout the system as repair seals and for new service connections. Occasionally unexpected fracture of the stainless steel clamps occurs with time-in-service periods as short as 1year. A failure analysis was conducted, including visual, microstructural, compositional, and mechanical characterization, to determine the cause and source of the degradation. Cracking of the clamps was limited to localized regions with the remainder of the clamp unaffected. Branched, brittle cracks were observed in the failure region and exhibited transgranular propagation. Based on the temperature, available moisture, stress level, and type of material used it was determined that the likely cause of failure was neutral pH, dilute chloride-induced stress corrosion cracking. Based on this failure analysis, geothermal or other buried heated water systems must consider protective measures or more SCC-resistant materials to prevent susceptible conditions from developing, compared to conventional water systems, to ensure maximum lifetime performance.

Single Wire Versus Double Wire Loops for Median Sternotomy Closure: Experimental Biomechanical Study Using a Human Cadaveric Model

Healing of median sternotomy requires reliable sternal fixation. Although both single and double wire kits are commercially available, no experimental study has compared the two closures in a human cadaveric model. We used a recently described human experimental cadaveric model to compare the stability of the closures. Sixteen fresh adult human cadaveric sternal plates with adjacent ribs were fixed with custom designed spiked stainless steel clamps and attached to a biomechanical testing device. Single No. 5 peristernal and double peristernal closures were tested. The stability of the unions was tested using perpendicular, repetitive force loads increasing from 0 to 800 Newtons at a rate of 0.5 mm/second. The two study groups did not differ in age or sex. No clamp failures or damage to the specimens occurred. The double peristernal closure exhibited a significantly lower permanent displacement than the single wire group, suggesting a superior strength and stability of that closure. To the extent to which this human cadaveric model resembles in vivo median sternotomy, these data suggest that the biomechanical stability of the peristernal double wire closure may exceed that of single wires.

Biomechanical comparison of median sternotomy closures

Background Poor healing of median sternotomy can significantly increase morbidity, mortality, and hospital costs. Effective union requires reliable sternal fixation. Although wire has proven the most reliable and widely used sternotomy closure material, no experimental studies have compared a large variety of wiring techniques in a human model. We developed an easily reproducible experimental model using cadaveric human sterna and compared several wiring methods to assess closure strength and stability. Methods Fifty-three fresh adult human cadaveric sternal plates with adjacent ribs were fixed with specially designed spiked stainless steel clamps and attached to a texture analyzer. Single peristernal and transsternal, alternating single peristernal and transsternal, figure-eight peristernal, figure-eight pericostal, and Robicsek closures using no. 5 stainless steel wires were tested. We evaluated bone density, stiffness, and displacement using perpendicular, repetitive variable force loads of 800 Newtons cycling at a rate of 0.5 mm/s. Results There were no significant differences in age, sex, or bone density in outcome measures of the sternal groups. No clamp failures or clamp damage to the specimens occurred. The single peristernal and alternating peristernal and transsternal closures proved superior in strength and stability ( p < 0.001). The figure-eight peristernal, then the single transsternal, then the Robicsek were next stablest groups in decreasing order. The figure-eight pericostal closure had the highest failure rate ( p < 0.001). Conclusions This novel model of sternotomy closure testing was reliable, inexpensive, and easily reproducible. The mechanical stability of peristernal and alternating peristernal and transsternal wires was significantly greater than that of the other tested methods. Pericostal figure-eight closures were not sufficiently stable to be considered a reliable method of primary sternotomy repair.

Biomechanical Porcine Model of Median Sternotomy Closure

Background. Healing complications following median sternotomy commonly include instability, nonunion, and infection. They are associated with a high mortality rate if mediastinitis supervenes. Closure complications are best avoided by improving stability at the union, but there has thus far been no widespread agreement among surgeons about relative superiority among the available closure techniques. Materials and methods. A biological sternotomy closure model was developed utilizing whole porcine sterna. A special stainless-steel clamp with multiple spikes was created to reliably attach the sterna to a biomechanical testing device. Results. Two wiring techniques, single peristernal and pericostal figure-eight, were used in 14 fresh cadaveric porcine sterna. The more rigid closure utilized single peristernal wires (P < 0.0001). There was no tissue associated with clamp spikes penetrating the specimen's layers, and there was no clamp displacement even at closure failure loads. Conclusions. The porcine sternotomy model is a valuable tool for comparing closure techniques based on geometrical and mechanical wiring patterns. The model's low cost and easy reproducibility make it a promising first step in sternotomy closure research. The stainless-steel clamp used in the porcine model provided reliable repeat specimen fixation.

Biomechanical Porcine Model of Median Sternotomy Closure

Background. Healing complications following median sternotomy commonly include instability, nonunion, and infection. They are associated with a high mortality rate if mediastinitis supervenes. Closure complications are best avoided by improving stability at the union, but there has thus far been no widespread agreement among surgeons about relative superiority among the available closure techniques. Materials and methods. A biological sternotomy closure model was developed utilizing whole porcine sterna. A special stainless-steel clamp with multiple spikes was created to reliably attach the sterna to a biomechanical testing device. Results. Two wiring techniques, single peristernal and pericostal figure-eight, were used in 14 fresh cadaveric porcine sterna. The more rigid closure utilized single peristernal wires ( P < 0.0001). There was no tissue associated with clamp spikes penetrating the specimen's layers, and there was no clamp displacement even at closure failure loads. Conclusions. The porcine sternotomy model is a valuable tool for comparing closure techniques based on geometrical and mechanical wiring patterns. The model's low cost and easy reproducibility make it a promising first step in sternotomy closure research. The stainless-steel clamp used in the porcine model provided reliable repeat specimen fixation.

A closed system for the filtration of Mycobacterium bovis liquid cultures using disposable capsule filters.

A filtration system was designed to sterilize large volumes of Mycobacterium bovis BCG Tokyo culture safely, needed to purify protein antigens for immunodiagnosis of bovine tuberculosis. A closed system consists of culture bottles connected to three disposable filter capsules of decreasing pore size in series: a depth prefilter over a 1.2 microns filter; 0.8 micron prefilter over a 0.45 micron filter; and a 0.2 micron sterile filter. Low air pressure (3 psi) forces liquid from below the bacillary pellicle. The system features a stainless steel clamp to hold rubber stoppers on the culture bottles, pleated filters to exclude bacillary clumps, a quick disconnector to minimize aerosols, and a closed system with plastic disposable filters that can be autoclaved as a unit without dismantling.

A Novel Reactor Design Configuration for Contamination Control and Improved Performance in the Polysilicon Doping Process Using POCl3

Conventional reactors have process limitations because of the hazardous nature of process by‐products. Experiments were conducted using a novel design quartz flange and stainless steel clamp exhaust configuration, along with a scavenger insulation block, which eliminated process by‐product buildup inside the reactor tube in the scavenger area. Experiments included variations in doping temperature, process time, , flow rate, and carrier and exhaust gas flow rates. This novele hardware design practically eliminates by‐product condensation and dripping outside the reactor, which reduces cross‐contamination and stainless steel corrosion problems and prevents potential minority carrier lifetime degradation. Equipment downtime is significantly reduced by eliminating autodoping and the need for frequent process tube steam cleans. Run capability is extended because of the new design, which also provides superior exhaust control and safer operation. The design also allows doubling of the number of wafers processed with improved sheet resistance uniformity. Regression equations were obtained for calculating sheet resistance, which can be a viable tool for process engineers. The new reactor configuration provides significant advantages in reduced equipment downtime, increased savings in material, and improved process performance.

Termites to Blame in Underground Leaks

Destruction of rubber gaskets at the joints of 8‐inch water lines by termites led to substantial amounts of water loss in Honolulu, Hawaii. Damaged gaskets were replaced, and stainless steel clamps were installed over the pipe joints.

Posterior Stabilization with an Interlaminar Clamp in Cervical Injuries: Technical Note and Review of the Long Term Experience with the Method

Abstract An alternative method of cervical fixation utilizing a stainless steel clamp is described. The clamp is applied to the adjoining laminae of involved vertebrae in those cervical dislocations and subluxations with posterior instability. The long term results of this method have been most satisfactory, as indicated by our follow-up of 51 patients treated during the last decade.

Posterior Stabilization with an Interlaminar Clamp in Cervical Injuries: Technical Note and Review of the Long Term Experience with the Method

An alternative method of cervical fixation utilizing a stainless steel clamp is described. The clamp is applied to the adjoining laminae of involved vertebrae in those cervical dislocations and subluxations with posterior instability. The long term results of this method have been most satisfactory, as indicated by our follow-up of 51 patients treated during the last decade.

Oxygenating Device for Live-Bait Wells

Details are given for the construction of a device for oxygenating live-bait wells and holding tanks. The unit is made from a 6-inch grinding wheel mounted in a stainless steel clamp. A 240-ft3 cylinder of industrial oxygen is used as the source of supply. The oxygen, released as small bubbles, is controlled by a pressure regulator on the oxygen cylinder. The oxygen flow rate at 5–35 psi was determined and the size of bubbles measured.

EFFECTIVE TESTING PROCEDURES FOR EVALUATING PLANT SANITATION

Summary Continuing problems with post-pasteurization contamination of milk and cream have stimulated dairy plants to undertake intensive programs to improve sanitation practices. Sources of contamination such as air, water, containers, fillers, pumps, joints, valves, cleaners and sanitizers have received more attention by the more progressive plants. Basic steps have been found to be necessary for improved keeping quality. These are a standardized reference test such as the Moseley 5 days at 45 F test, application of trouble shooting procedures, and application of additional sanitary measures. Comparisons using the Moseley keeping quality test and CVT test showed little correlation between them. A newly designed sampler has provided means of monitoring sanitary conditions and product keeping quality. It is a 3/8-inch drilled hole with a rubber insert clamped in by a stainless steel clamp. The sampler has withstood any pressure applied to it internally under normal dairy processing and can be permanently located in any pipe line system. Product filling equipment is still the main contributor of contamination. It was found that manual cleaning instead of CIP cleaning was a necessity in equipment that had many product sealing joints. These areas particularly vulnerable due to heavy lubricants often used. Spraying filling areas with sanitizers during processing is essential. Plant conditions change every hour during production, therefore, adjustments in procedures to avoid contamination must be exercised. Cursory examination of plants to evaluate sanitation is insufficient. The best criterion still is the bacteriological and flavor condition of the product at the consumer level.

Apparatus and technic for the administration of intracavitary radioactive isotopes.

The method of administration of radioactive isotopes in the treatment of pleural effusions and ascites associated with cancer will vary according to the therapeutic technic (1–5). A procedure with a suitable apparatus that utilizes an economical and sterile disposable package is described in this paper. The apparatus, shown in Figure 1, consists of: polyethylene or nylon tubing with an interior diameter of 0.70 inch; 4 stainless steel clamps; 3 No. 15 hypodermic needles of 3 1/2 inches length; 1 ampule of 5.0 c.c. Evans blue; 500 c.c. isotonic saline solution; 1 Cly-Q-Pak2; 2 Donopak 242; one Y connector.2 All the equipment is supplied sterile or can be sterilized. The radioactive isotope, whether colloidal chromic phosphate (P32) or colloidal gold (Au198), can be obtained in the exact amount prescribed. The entire apparatus is assembled within a few minutes under sterile conditions (Fig. 2). Before the hypodermic needles are inserted into the radioactive isotope vial, the air is removed from the tubing b...