Laser Cut Research Articles

Minimizing Thermal Damage During Thulium Laser-Assisted Partial Arytenoidectomy: Pulsed Versus Continuous Cutting in an Ex-Vivo Calf Model.

The 2 µm-wavelength thulium laser is an effective cutter during partial arytenoidectomy, but thermal trauma can damage adjacent laryngeal tissue. Pulsing laser energy may reduce trauma when compared to continuous-wave cutting. This study measured temperature changes, thermal trauma, and time to complete partial arytenoidectomy, with and without pulsing, in an ex-vivo calf model. Tissue temperature and time to complete a trans-cartilaginous cut were measured during partial arytenoidectomy on ex-vivo calf vocal folds (N = 24) using a thulium laser in continuous-wave (CW, N = 12) and pulsed-wave (PW, N = 12) modes. Energy was 5 W for CW and PW cuts; pulse-widths were 250, 500, and 750 ms. Thermal damage was analyzed histologically by measuring the depth of lactate dehydrogenase (LDH) inactivation perpendicular to the laser-cut edge at the vocal process. Paired t-tests compared CW and PW modes. Change in temperature was lower using CW (6.5°C) compared to PW modes (250 ms = 18°; 500 ms = 16°; 750 = 19°; P < .05). Trans-cartilaginous cuts were completed faster using CW (37 seconds) compared to PW (250 ms = 136 seconds; 500 ms = 61 seconds; 750 = 44 seconds; P < .05), and both modes delivered the same total Joules. The average depth of LDH depletion (thermal damage) was similar for all cuts. 1. Thulium laser cuts in continuous-mode unexpectedly produced less tissue heating yet created similar thermal damage than pulsed-mode cuts during simulated partial arytenoidectomy. 2. Trans-cartilaginous cuts were completed significantly faster in continuous-mode as compared to pulsed-mode cutting. 3. Pulsing the thulium laser does not minimize thermal damage compared to continuous wave cutting during thulium laser-assisted partial arytenoidectomy.

Selective laser capsulotomy complications: Management and prevention.

To report how to manage and prevent the incomplete laser cut and following uncut tags of anterior capsular lens, performed using the selective laser capsulotomy. We describe three possible approaches: peeling the anterior capsulotomy disc with forceps, breaking the tags using the cystotomy needle tip, or cutting them using a 23-G vitrectomy scissors. Using the 23-G vitrectomy scissors resulted in no complication. Peeling the anterior capsulotomy using the forceps instead caused zonular stress with subsequent risks of zonular dialysis, whereas using the cystotomy needle tip resulted in irregular capsulotomy rim and weakness all along the capsulotomy edge where micro tears caused a tear during the rest of cataract surgery. Incomplete laser cut and subsequent discontinuous capsulotomy results in the presence of multiple tags which create strong adherence between the central capsulotomy disc and the peripheral capsule. Key steps of the procedure to prevent an incomplete laser cut, which are the anterior lens capsule staining and laser beam focusing, and how to correctly manage them, which may shorten the learning curve and enhance the outcomes.

Low-pressure plasma treated polycarbonate and polymethyl methacrylate (PMMA) sheets with different surface patterns to change their surface properties

Low-pressure plasmas of carbon tetrafluoride (CF4), oxygen (O2), and air were used to treat the surfaces of polycarbonate (PC) and polymethyl methacrylate (PMMA) to achieve a variety of surface attributes, such as hydrophilicity, hydrophobicity, and surface free energy. Patterns of straight line, triangular and square shapes with different sizes e.g., 0.5 mm, 0.75 mm, and 1 mm dimensions as templates were constructed from stainless-steel sheets with a thickness of 1 mm, via laser cutter, were used to induce the corresponding shape of the functionality on PC and PMMA surfaces during plasma gas treatment were also investigated. The untreated PC and PMMA surfaces have a contact angle (θ) value of 70°±0.47° and 77°±0.80°, respectively. As expected upon CF4 plasma treatment, their contact angle values were increased to 109.04°±0.35° and 105.76°±0.61°, respectively; whereas the air plasma treated surfaces became more hydrophilic with the contact angle values of 29.34°±0.14° and 43.99°±0.22°, correspondingly. Moreover, O2 plasma treated surfaces became more hydrophilic with the contact angle values of 25.32°±0.77° for PC and 39.94°±2.05° for PMMA. Also, surface free energy (SFE) values were decreased to 11±0.87 mN/m from 41.16±0.42 mN/m for PC and to 12.11±1.53 mN/m from 35.93±1.12 mN/m for PMMA upon CF4 treated surfaces. Furthermore, SFE values were increased to 57.59±1.12 and 62.13±1.15 mN/m for PC and PMMA after air plasma treatment. PC surface's, advancing and receding contact angles were determined as 101.48°±0.33° and 65.60°±0.11° respectively for 34.77°±0.50° slide-off angles. Moreover, the advancing and receding contact angles for PMMA were found as 93°±0.64° and 61.60°±1.19°, respectively with a sliding angle of 24.49°±1.14°. X-ray Photoelectron Spectroscopy (XPS) analysis results confirmed the fluorination and oxidation of both PC and PMMA after CF4 and O2 plasma treatments, individually. PC and PMMA surfaces were treated multiple times with CF4 and Air, Air and CF4, O2 and CF4, and CF4 and O2 plasmas in succession. After multiple treatment, PC and PMMA surfaces contact angle values were decreased as low as 10.62°±0.88° and 14.96°±0.2°, respectively.

Three-dimensional biofabrication of nanosecond laser micromachined nanofibre meshes for tissue engineered scaffolds.

There is a high demand for bespoke grafts to replace damaged or malformed bone and cartilage tissue. Three-dimensional (3D) printing offers a method of fabricating complex anatomical features of clinically relevant sizes. However, the construction of a scaffold to replicate the complex hierarchical structure of natural tissues remains challenging. This paper reports a novel biofabrication method that is capable of creating intricately designed structures of anatomically relevant dimensions. The beneficial properties of the electrospun fibre meshes can finally be realised in 3D rather than the current promising breakthroughs in two-dimensional (2D). The 3D model was created from commercially available computer-aided design software packages in order to slice the model down into many layers of slices, which were arrayed. These 2D slices with each layer of a defined pattern were laser cut, and then successfully assembled with varying thicknesses of 100 μm or 200 μm. It is demonstrated in this study that this new biofabrication technique can be used to reproduce very complex computer-aided design models into hierarchical constructs with micro and nano resolutions, where the clinically relevant sizes ranging from a simple cube of 20 mm dimension, to a more complex, 50 mm-tall human ears were created. In-vitro cell-contact studies were also carried out to investigate the biocompatibility of this hierarchal structure. The cell viability on a micromachined electrospun polylactic-co-glycolic acid fibre mesh slice, where a range of hole diameters from 200 μm to 500 μm were laser cut in an array where cell confluence values of at least 85% were found at three weeks. Cells were also seeded onto a simpler stacked construct, albeit made with micromachined poly fibre mesh, where cells can be found to migrate through the stack better with collagen as bioadhesives. This new method for biofabricating hierarchical constructs can be further developed for tissue repair applications such as maxillofacial bone injury or nose/ear cartilage replacement in the future.

A methodological framework for the integration of 3D virtual prototyping into the design development of laser-cut garments

3D virtual prototyping for garment development, although not much exploited and appreciated by the clothing industry in the early days of its appearance two decades ago, has now been explored (research-wise) extensively especially in the pandemic period and its impact on the whole supply chain of garments and fashion products. This virtual prototype which allows the company to visualize the status and condition of a clothing product that may be thousands of kilometers away, providing insights into how products can be better designed, manufactured, operated and serviced before companies invest in physical prototypes and assets, is often called digital twin. At the same time, laser-cut as a creative design technique on clothing materials have emerged in recent times, as fashion moguls are seeing the benefits that the technology presents. Laser cut technology with its benefits of accuracy, speed, precision, applicability in various materials, flexibility in geometry, interoperability with other systems like CAD/CAM and CIM, sustainability in resources and source of inspiration for several upcoming designers, provides an excellent approach for creating bridges between the past, the present and the future in history of fashion design. The aim of this paper was to provide a decision-making framework for the selection of an effective digital twinning process with the use of two different 3D virtual prototyping tools. For this purpose, a methodological framework is proposed which guides the creator according to the final use of the digital garment twin: evaluation of actual fit and actual representation of the produced physical, or as a shared digital asset for an exclusive digital environment.

Fabrication of ITO microelectrodes and electrode arrays using a low-cost CO2 laser plotter.

Good electronic (Rs = ∼5 Ω sq-1) and optical properties (transmittance: >83%) make indium tin oxide (ITO) an attractive electrode substrate. Despite the commercial availability of high-quality ITO and some low-cost methods for direct deposition being in use by now, the definition of patterns is still a concern. Putting their popularity and extensive use aside, the manufacturing of ITO electrodes so far lacks a rapid, highly reproducible, flexible, cost-effective, easy patterning process that could surpass difficult, time-consuming techniques such as lithography. Herein, we present a low-cost method based on CO2 laser irradiation for preparing ITO microelectrodes and electrode arrays. Electrodes of different sizes and shapes were examined to identify the performance of the proposed methods. Direct ablation of the ITO layer was optimized for rectangular electrodes of 25, 50, and 100 μm in width, while laser cutting of scotch tape stencils and subsequent wet etching were used to create circular electrodes with a diameter of 1.75 mm. A multielectrode array system consisting 8 of these circular electrodes was fabricated on a (25 × 25) mm2 plate, characterized electrochemically through cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM), and as an example application used for monitoring the anchoring behavior of HeLa and HepG2 cell cultures through cell-based electrochemical impedance spectroscopy. Together, the direct ablation method and preparation of laser cut stencils form a complete toolbox, which allows for low-cost and fast fabrication of ITO electrodes for a wide variety of applications. To demonstrate the general availability of the method, we have also prepared a batch of electrodes using a laser plotter in a local printing shop, achieving high intra-workshop reproducibility.

Selective laser ablation for in situ fabrication of enclosed channel porous-media microfluidic analytical devices.

This work describes a new method for fabrication of enclosed channel porous-media microfluidic analytical devices using selective laser ablation. Microfluidic structures can be readily produced inside the enclosed devices within two fabrication steps. A sheet of porous material was first sandwiched and bonded between two sheets of polymeric film. The porous substrate inside the film layers was then selectively ablated using a laser cutter to create hollow barriers for microfluidic channels. Selective ablation of only the porous layer was achieved because the porous substrate layer is susceptible to ablation by the laser beam, whereas the film layer is resistant to laser ablation due to its light transmission properties. This selective laser ablation processing is not limited by laser type. As a proof-of-concept, two different laser systems, a 10.6 μm CO2 laser and a 455 nm diode laser, were employed for this purpose. A variety of porous materials, including cellulose, nitrocellulose, and glass microfiber, were combined with a wide variety of polymeric films to fabricate enclosed microfluidic devices. The developed method is versatile; depending on material combination and number of layers of materials in the devices, enclosed microfluidic devices with 2D, passive 3D, or compression-activated 3D fluid flow can be created. Quantitative assays for albumin, glucose, and cholesterol in human serum performed using devices produced via this method demonstrated the utility of this fabrication approach. This unique, simple, and scalable method for fabrication of enclosed microfluidic devices not only ensures protection of devices from contamination and prevention of fluid evaporation, but also offers a method for commercial fabrication of porous-media analytical devices.

Effect of preheating during laser metal deposition on the properties of laminated bending dies

Metal-laminated tooling provides a fast and cheap manufacturing concept. In this study, laser metal deposition (LMD) is used for reducing and eliminating the stair step effect in a metal-laminated bending die. Preheating could decrease the undesired residual stresses in additive manufacturing, thus a systematical analysis of the effect of preheating of the laminae on the surface quality and mechanical properties of the bending die is performed. Ferritic steel sheets (S355 MC) with a thickness of 2 mm are laser cut and stacked up to manufacture the laminated bending die with a radius of 6 mm. The sheets are joined and the stair steps are filled with LMD with stainless steel powder 316L-Si. The initial temperature of the tool sheets (substrates), beside room temperature, is elevated up to 300 °C. The effect of the preheating on the surface roughness, shape deviation, hardness, and residual stresses of the die are investigated. The mean height of the surface increases by 59% at elevated temperatures. However, the tensile residual stress parallel to the weld direction at the middle of the deposited area decreases only around 25%. The functionality of the forming tools manufactured by this method is proven by bending of DC06 and HC380LA sheets.

When the Beetles Hit the Fan: The Fan-Trap, an Inexpensive, Light and Scalable Insect Trap under a Creative Commons License, for Monitoring and Experimental Use.

Monitoring is an important component in pest management, to prevent or mitigate outbreaks of native pests and to check for quarantine organisms. Surveys often rely on trapping, especially when the target species respond to semiochemicals. Many traps are available for this purpose, but they are bulky in most cases, which raises transportation and deployment issues, and they are expensive, which limits the size and accuracy of any network. To overcome these difficulties, entomologists have used recycled material, such as modified plastic bottles, producing cheap and reliable traps but at the cost of recurrent handywork, not necessarily possible for all end-users (e.g., for national plant-protection organizations). These bottle-traps have allowed very large surveys to be conducted, which would have been impossible with standard commercial traps, and we illustrate this approach with a few examples. Here, we present, under a Creative Commons BY-SA License, the blueprint for a fan-trap, a foldable model, laser cut from a sheet of polypropylene, which can rapidly be produced in large numbers in a Fab lab or by a commercial company and could be transported and deployed in the field with very little effort. Our first field comparisons show that fan-traps are as efficient as bottle-traps for some Scolytinae species and we describe two cases where they are being used for monitoring.

Evolution of as-solidified and heat-affected microstructures under different thermal manufacturing processes for 316 L stainless steel

In this study, laser-arc welding (LAW), laser welding (LW), and laser cutting (LC) of 316 L stainless steel plates were selected to comparatively study melting-solidifying and heat-affected zones (MSZ, HAZ). Variations of morphology, crystalline orientation, and phase interfaces were systematically investigated from LAW to LW and LC. In the MSZ, δ phase presented a dramatic decrease in fraction and size with degenerated dendritic and increasingly dispersed features while γ grains were gradually refined. Special orientation relationships Bain, K.-S., N.-W. and G.-T. were frequently observed in re-solidified zones and δ coarsening regions of HAZ. Depending on the solidification speed, temperature gradient, and solid/liquid interface instability caused by manufacturing processes, δ and γ refinements in MSZ and HAZ from LAW to LW and LC were attributed to the S/L instability, lowered high-temperature duration，and variable epitaxial growth on previously formed δ (LW) or γ (LC). • Evolution of microstructure and microtexture in as-solidified and heat affected zones were compared. • The fraction and arrangment of δ phase was primarily controlled by the solid precipitation duration. • Grain size and orientation of γ phase was both decided by previously formed δ phase at a low temperature gradient or γ phase at a high one.

Flexible Paper-Based Immunosensor for the Detection of Specific Cancer-Derived Exosomes

This study aims at an electrochemical paper-based device for the selective and sensitive detection of exosomes as an economic and flexible platform. Using a laser cutter, a three-electrode platform was patterned on a hydrophobic paper, and then synthetic carbon and silver ink were screen-printed on the paper. Anti-human CD9 antibody was covalently attached to the surface of a carbon ink electrode enriched with graphene oxide aerogel/CoFe2O4@chitosan nanocomposite. The immobilization, incubation and binding time of the capture antibody were investigated as effective parameters. Under optimum conditions, the differential pulse voltammetry (DPV) was used to establish a calibration plot that covered 500 to 5 × 106 exosoms μl−1 with a detection limit of 100 exosome μl−1. This method was implemented successfully for the detection of exosomes in a serum sample. As the results show, the fabricated biosensor is capable of detecting exosomes for the early diagnosis of cancers.

Laser cutting of plasma-sprayed refractory products made of aluminum oxide

The possibility of laser cutting of plasma-sprayed refractory products made of aluminum oxide was investigated. The industrial laser complex KS-5VDM1-3 Navigator (VNITEP, Russia), equipped with an LS-3 ytterbium fiber laser with a power of 3 kW, was used to work out the cutting conditions. It was found that immediately after the completion of the plasma spraying process, the phase composition of the article material is a set of various modifications of aluminum oxide. Subsequent heating of these items leads to a series of polymorphic transformations accompanied by changes in the volume and density of the item material. The process ends when all polymorphic modifications of aluminum oxide pass into the only stable phase α-Al2O3 (corundum). It was shown that laser cutting of plasmasprayed aluminum oxide products is possible only when the process of transition of all its phase modifications to corundum is completely completed. Otherwise, a sharp change in the volume of the product material, caused by polymorphic transformations occurring under conditions of a high temperature gradient that occurs during laser cutting, leads to the destruction of the product. Plasmasprayed product, the material of which is entirely α-modification of aluminum oxide (corundum), is not afraid of high temperature gradients and is easily laser cut without destruction. Cutting data can vary widely. The cutting technology of plasma-sprayed refractory products made of aluminum oxide has been mastered at the Scientific and Educational Center for the Implementation of Laser Technologies at the Vladimir State University. Ill. 3. Ref. 13. Tab. 2.

Abstract 15506: Optical Mapping in Atrial Engineered Heart Tissues Reveals Proarrhythmic Potential of the Anti-AF Agent Vernakalant

Pharmacotherapy for atrial fibrillation (AF) is confounded by ventricular proarrhythmia. Vernakalant (VER) belongs to a class of atrial selective channel blockers developed in attempts to convert AF safely. Yet, robust analysis of the effects of VER in human based tissues has not been performed. We hypothesized that engineered heart tissues (EHT) composed of atrial (A) or ventricular (V) human iPSCs would provide a robust platform for quantitative analysis of chamber specific electrophysiological (EP) effects of VER. Methods: iPSCs were differentiated into cardiomyocytes using biphasic Wnt signaling, insulin, and lactate purification. Atrial-like myocytes were enriched by adding 0.75 μM retinoic acid on days 4-6 to promote atrial gene expression and specification. Myocytes were seeded onto cryosectioned, laser cut and decellularized myocardial tissues and cultured under isometric conditions. EHTs were stained with high dose, water soluble di-2-ANEPEQ to enhance signal-to-noise while avoiding toxicity. Results: Staining with 25 μM di-2-ANEPEQ provided high fidelity optical AP signals that allowed comprehensive characterization of the EP substrate. A-EHT exhibited significantly shorter AP durations than V-EHT reflecting greater repolarizing drive (APD80, 180 ms vs 367 ms; p &lt; 0.0001, n = 4-5). Consistent with its role as an atrial-selective blocker, VER increased APD80 only in A-EHTs (180 ms vs 258 ms, p = 0.0027, n = 5). This beneficial property for combatting AF was countered by marked slowing of A-EHT conduction and AP upstroke velocity (20.6 cm/s vs 11.7 cm/s, p = 0.027, n = 5). Conclusions: Optical mapping of chamber specific EHTs confirms atrial specific nature of VER as an atrial repolarization prolonging agent but raises unexpected concerns regarding potential proarrhythmic toxicity related to atrial conduction slowing.

Efficacy of Virtual Equipment Training

The University of Ottawa faculty of engineering, in Ottawa Canada, is home to multiple rapid prototyping facilities as well as entrepreneurship spaces. This includes a makerspace, a machine shop and a design space for any student to use free of charge. Due to COVID-19 the spaces were either shut down or running virtual activities where possible. In the absence of any significant virtual content for learners, virtual computer simulations and virtual reality simulations were developed for various technologies including a manual mill and lathe, a laser cutter and soldering. Even as the COVID-19 restrictions are being lifted, the virtual simulations will be used as a pre-training introduction for in-person sessions. This paper aims to understand how well the virtual training simulations compare and compliment the in-person training for different equipment. Factors considered are the level of previous knowledge and level of interest in the equipment. The same assessment will be given to 3 groups of participants: those who have only done the virtual training, who have only done the in-person training and who have done both. The results from each group will be compared and analyzed to determine the efficacy of the virtual simulation and what advantages it has as a pre-training resource.

Porous Cellulose Substrate Study to Improve the Performance of Diffusion-Based Ionic Strength Sensors.

Microfluidic paper-based analytical devices (µPADs) are leading the field of low-cost, quantitative in-situ assays. However, understanding the flow behavior in cellulose-based membranes to achieve an accurate and rapid response has remained a challenge. Previous studies focused on commercial filter papers, and one of their problems was the time required to perform the test. This work studies the effect of different cellulose substrates on diffusion-based sensor performance. A diffusion-based sensor was laser cut on different cellulose fibers (Whatman and lab-made Sisal papers) with different structure characteristics, such as basis weight, density, pore size, fiber diameter, and length. Better sensitivity and faster response are found in papers with bigger pore sizes and lower basis weights. The designed sensor has been successfully used to quantify the ionic concentration of commercial wines with a 13.6 mM limit of detection in 30 s. The developed µPAD can be used in quantitative assays for agri-food applications without the need for any external equipment or trained personnel.

Component modelling of 3D laser cut joints with CHS columns and through-all members

3D laser cutting technology is a new automatised industrial process allowing the development of a range of novel applications in civil engineering. Its main advantage derives from the possibility to manufacture easily tridimensional cutting shapes with high precision (accuracy of about 10μm), minimising the hole size, optimising the welding quantity and costs. This technology is up to thirty times faster than traditional methods since all the operations are programmed and fully realised by the machine, avoiding any intervention of operators, eliminating human errors and increasing the quality level.3D-LCT allows joining hollow section profiles to through-all members with a straightforward production process. The main feature of joints with passing-through profiles is the higher flexural strength and stiffness compared to traditional connections without additional costs. Nevertheless, considering the recent development of these joints, currently, there are no codified rules, and their design usually implies the use of FEM. This work aims to take a step towards developing simple analytical tools for designing and modelling such connections through the component method, currently codified in EC3 part 1.8. Within this framework, the subject of the paper is the study of the behaviour of one of the main elementary components characterising the response of beam-to-column joints with CHS columns and I-beams, which is the “passing-through plate transversally welded to the column in tension/compression”. This component idealises the behaviour of the passing-through beam flange plates (in tension/compression) at the attachment with a CHS column. Its response is significant for the overall joint behaviour because it governs the deformability of the connection and may limit the joint’s resistance due to the CHS tube’s local failure. This paper presents the results of three monotonic tests of sub-assemblies of this joint component, showing the typical failure mode and the component behaviour. Subsequently, a FE model is built with ABAQUS software, carrying out parametric studies to individuate the main parameters influencing the behaviour of these joints. Finally, equations to predict the stiffness and strength are provided, showing the accuracy obtained.

Low-Cost Laser-Acoustic PVC Identification System Based on a Simple Neural Network.

Desktop laser cutters are an affordable and flexible rapid-prototyping tool, but some materials cannot be safely processed. Among them is polyvinyl chloride (PVC), which users usually cannot distinguish from other, unproblematic plastics. Therefore, an identification system for PVC applicable in a low-cost laser cutter has been developed. For the first time, this approach makes use of the laser-ablative sound generated by a low-power laser diode. Using a capacitor microphone, a preprocessing algorithm and a very simple neural network, black PVC could be detected with absolute reliability under ideal conditions. With ambient noise, the accuracy dropped to 80%. A different color of the material did not influence the accuracy to detect PVC, but a susceptibility of the method against a color change was found for other materials. The ablation characteristics for different materials were recorded using a fast-framing camera to get a better insight into the mechanisms behind the investigated process. Although there is still potential for improvements, the presented method was found to be promising to enhance the safety of future desktop laser cutters.

Human Gingival Fibroblast Attachment to Smooth Titanium Disks with Different Surface Roughnesses.

Peri-implantitis is a significant problem associated with dental implants. It has been hypothesized that creating a soft-tissue seal around the implant neck prevents peri-implantitis. This study aims to clarify the effects of the surface smoothness of titanium disks on soft tissues. Thus, titanium disks were prepared through electrolytic composite polishing (ECP), sisal buffing (SB), hairline polishing (HP), and laser cutting (LC). The surface roughness values of seven items was measured. For ECP, SB, HP, and LC samples, the Ra values were 0.075, 0.217, 0.671, and 1.024 μm and the Sa values were 0.005, 0.115, 0.500, and 0.676, respectively, indicating that the surface roughness was remarkably lower with ECP. Moreover, the Wsk values for ECP, SB, HP, and LC were 0.521, 1.018, -0.678, and -0.558, respectively. The smooth surfaces produced by ECP and SB were biased toward the concave surface, whereas those produced by HP and LC were biased toward the convex surface. The Rku values for ECP, SB, HP, and LC were 2.984, 11.774, 14.182, and 26.232, respectively. Only the ECP exhibited a moderate bias peak and produced an extremely smooth surface. The contact angles in the cases of ECP, SB, HP, and LC were 60.1°, 66.3°, 68.4°, and 79.3°, respectively, indicating the hydrophobicity of the titanium disks. Human oral fibroblasts were then incubated on each disk for 24 and 48 h to measure cell attachment, and no significant differences were observed. The differences in Ra and Sa did not affect cell attachment. Therefore, by applying ECP to the abutment or implant neck, the cell attachment required for soft-tissue formation while preventing bacterial adhesion can be achieved.

CNC Enabled Wood/Metal Composite Construction of (Relatively) High Performance Sailing Yachts

One problem for high performance yachts is to produce a light enough, strong enough structure. Modern fiberglass “composite” construction achieves this, but at substantial cost for the molds so fiberglass is expensive for limited construction. However, “composite” is a combination of any two materials. Before fiberglass, “composite” comprised wood planking over metal framing. Prince Edward’s, (King Edward VII) yacht Britannia was pine over steel and was a very successful racer. This system is used by a few builders of large, mainly “revival” design yachts, but it is feasible for many boat types and could reduce the cost and increase availability of limited run yachts. Modern composite construction is enabled by CAD/CAM/CNC design and cutting, engineered wood, modern coatings and adhesives, non-metallic fastenings, welding, and even aluminum. The major framing structure is cut out of metal by plasma arc, water jet, or laser cutters using standard metal industry techniques and equipment. The shell is strip planking, cold molding, carvel or lap strake planking, or plywood. Planks or shell “plating” can even be CNC cut for additional labor reduction. This method can be cost effective for a one-off or limited production boat compared to making a mold for a fiberglass boat or all wood construction. Finally, large heavy timbers are not required which not only reduces labor, but allows sustainable timber resources and sequesters the carbon in the tree in a form that hopefully will last for some decades.

Hierarchical Slice Patterns Inhibit Crack Propagation in Brittle Sheets

By introducing hierarchical patterns of load-parallel cuts into axially loaded brittle sheets, the resistance to propagation of mode-I cracks is very significantly enhanced. We demonstrate this effect by simulation of two-dimensional beam network models and experimentally by testing paper and polystyrene (PS) sheets that are sliced with a laser cutter to induce load-perpendicular hierarchical cut patterns. Samples endowed with nonhierarchical reference patterns of the same cut density and nonsliced sheets are considered for comparison. We demonstrate that hierarchical slicing can increase failure load, apparent fracture toughness, and work of fracture of notched paper and PS sheets by factors between 2 and 10.