Laser-assisted Technique Research Articles

Stapes surgery in patients with a small air-bone gap.

The objective of this study was to determine hearing outcomes in patients undergoing stapes surgery with a preoperative air-bone gap (ABG) <21.25 dB. Patients with a unilateral or bilateral preoperative ABG <21.25 dB undergoing primary stapes surgery were identified from a database of all stapes surgeries performed in a tertiary center over 15 years. A total of 254 ears met the inclusion criteria. The primary outcome measure was the degree of closure of the preoperative ABG. A secondary outcome measure was improvement in bone-conduction thresholds at 4 kHz. All patients underwent stapes surgery under local anesthesia. Ossicular reconstruction was achieved using a SMart 360 nitinol fluoroplastic piston (Gyrus ACMI, Inc.; Southborough, Mass.), and complete posterior crurotomy was performed with a KTP laser. Hearing was assessed with clinical voice testing immediately postoperatively and with pure-tone audiometry at 6 weeks postoperatively. A total of 248 ears (97.6%) demonstrated ABG closure to <10 dB. Bone-conduction thresholds showed an increase in 114 (44.9%), no change 74 (29.1%), and a decrease in 66 (26.0%). There is a slight increase in the risk of stapes mobilization in ears with a small ABG when compared to those with larger ABGs; however, this can be overcome by using a laser-assisted technique in combination with good surgical experience. The benefit in terms of hearing aid avoidance and the restoration of symmetrical hearing is both achievable and significant for the patient.

Laser-Assisted Delivery Of Cold Atmospheric Plasma In Unresectable Cutaneous Metastasis In Melanoma Patients

According to the World Health Organization, the incidence of melanoma is increasing faster than that of any other major cancer in the world. Melanoma is the fifth most common cancer in the United States, posing a substantial health and economic burden. Treatment of early and multiple cutaneous unresectable metastasis in melanoma patients is a major therapeutic problem. Cold atmospheric plasma (CAP) contains electrons, charged particles, radicals, various excited molecules, UV photons, and transient electric fields. These various compositional elements have the potential either to enhance cellular activity, or to disrupt it. In particular, based on this unique composition, CAP could offer a minimally-invasive surgical approach allowing for specific cancer cell or tumor tissue removal without influencing healthy cells. Topical application of treatment agents is a basic principle of dermatological therapy. However, the effective barrier function of the skin significantly impairs the bioavailability of most topical drugs. Fractional ablative lasers represent an innovative strategy to overcome the epidermal barrier in a standardized, contact-free manner. The bioavailability of topical agents can be significantly enhanced using laser-assisted delivery. Ablative fractional laser resurfacing creates vertical channels that might assist the delivery of topically applied cold plasma into cutaneous melanoma metastasis. For lesions refractory to elective treatments, the laser-assisted drug delivery technique combined with cold atmospheric plasma may present a new potential option. We report on a pilot study showing a proof of concept for enhancing topical cold atmospheric plasma permeation into depth by ablative fractional laser technique.

Influence of high heat load on flow and containment of an inclined air-curtain (IAC) fume hood

ABSTRACTThe inclined air-curtain (IAC) fume hood has been reported to have “almost null leakage”[1] at low suction flow rates when operated at regular temperatures. However, previous research has not investigated the performance or optimized operating parameters when a high heat load is used in the IAC fume hood. For the present work, the effects of a high heat load on the flow field and contaminant leakage characteristics of the IAC fume hood were examined. The heat load was supplied to an IAC hood according to the standard method of EN14175-7:2012. The laser-assisted smoke flow visualization technique was employed to identify the characteristic flow patterns. The standard tracer-gas concentration test method (EN14175-3:2003) was used to examine the leakage levels of the IAC fume hood under static conditions, sash movement, and simulated walk-by conditions. When the IAC fume hood was operated at a high heat load, the static test results showed negligibly small leakage levels at a face velocity greater than or equal to only 0.19 m/s (37.4 ft/min). The sash movement and simulated walk-by test results showed that to obtain negligibly small leakage levels at high heat load operation, the IAC fume hood required a face velocity greater than or equal to 0.32 m/s (63 ft/min). In addition, the IAC fume hood exhibited a superior hood containment performance with low energy consumption when compared with conventional fume hoods operated at a high heat load.

Velocity fields and mixing properties of swirling double-concentric jets using two separated circular disks as center bodies

This study investigated the flow features, turbulence characteristics, and mixing properties of swirling double-concentric jets by using two separated circular disks as the center bodies. The upstream circular disk was placed at the exit of the central jet, while the downstream circular disk was located at a short distance downstream the upstream circular disk. The laser-assisted smoke-wire technique was used for flow visualization, particle image velocimetry (PIV) was utilized to investigate the velocity field, and the tracer gas concentration detection method was used to examine mixing property. When one circular disk was used as the center body, the flow patterns obtained through flow visualization and PIV measurement revealed two pairs of counter-rotating vortices existing in the near wake. The central jet penetrated the recirculation zone without any reversal, so low mixing between the central jet fluids and the annular swirling jet was observed. When two circular disks were used as the center body, the central jet momentum was transferred from the axial direction to the radial direction, and then it was dispersed and diffused into the annular swirling jet in the wake. Two flow modes were identified in the near wake: close-top toroidal wake and turbulent reverse-flow wake. In both characteristic flow modes, flows on the central axis were reversed in the near wake region. The axial and radial turbulence intensities were increased, and large values were observed inside the recirculation zone. Consequently, the carbon dioxide released from the central jet exit detected in the wake of the two-disk case was drastically lower than that of the one-disk case. The maximum improvement of mixing capabilities of the swirling double-concentric jets could attain about 96% when one circular disk was replaced by two disks.

Laser-assisted selective lithography of reduced graphene oxide for fabrication of graphene-based out-of-plane tandem microsupercapacitors with large capacitance

We present a laser lithography technique that uses a focused laser beam to fabricate out-of-plane tandem microsupercapacitors (MSCs) from reduced graphene oxide (rGO) with large areal capacitance. By controlling the depth of focus in a laser beam focused by an objective lens during laser lithography on a graphene oxide (GO) film, a rGO/GO/rGO structure is formed in the GO film, and subsequently, two independent interdigitated electrodes (IDEs) were fabricated on the top and bottom surfaces of the GO film. The out-of-plane tandem MSC with a parallel assembly of two rGO-IDEs showed two times larger areal capacitance than an in-plane single MSC with one rGO-IDE in the same MSC device footprint. The laser-assisted selective lithography technique using a focused laser beam developed in this study can be further applied to improve the energy density of MSCs without increasing the electrode area by vertically stacking multiple out-of-plane tandem IDEs.

Postoperative Clinical Evolution of Edentulous Patients Treated by Guided Bone Regeneration Using Xenograft Bone Substitute and Collagen Membrane

This paper aims to assess the postoperative evolution of edentulous patients treated by guided bone regeneration technique using a xenograft bone substitute (Cerabone) and collagen membrane. A group of 40 patients, programmed for guided bone regeneration, randomly divided between laser-assisted technique and scalpel technique, were investigated to compare the postoperative evolution, healing time and prevalence of new bone formation, graft stability and inflammatory reactions. The guided bone regeneration technique associated with laser or scalpel technique offers reliable and predictable treatment results in the implant-prosthetic treatments. The accelerated healing time recommends the laser technique in the surgical procedures used for the alveolar augmentation.

Investigation on a laser-assisted radiation thermometry technique.

A laser-assisted radiation thermometry (LART) technique is proposed for the surface temperature measurement of objects at high temperatures, which obviates the need for the knowledge of specimen emissivity. It uses a modulated laser to excite a temperature rise at the specimen surface, which is remotely sensed through thermal radiation detection at two infrared wavelengths. The theoretical analysis indicates that the surface temperature of the specimen can be inferred from the detected signals, independently of specimen emissivity. Measurements were performed on an oxidized Inconel 600 sample over a temperature range of 1120-1265 K. Measured surface temperatures were compared with those deduced from thermocouple measurements made inside the sample, and indicated less than 3% differences between them for sample surface temperatures above 1200 K.

Density functional theory molecular modeling and antimicrobial behaviour of selected 1,2,3,4,5,6,7,8-octahydroacridine-N(10)-oxides

A series of 9-substituted 1,2,3,4,5,6,7,8-octahydroacridine-N(10)-oxides is evaluated against 12 bacterial and fungal strains, for their microbicidal and anti-pathogenic features. The largest spectrum of the antibacterial activity is evidenced for the nitro- (2b) and hydroxy- (5b) N-oxides, followed by the amino-N-oxide (3b). Density functional theory (DFT) modeling of the molecular structure and frontier molecular orbitals, i.e. highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO), is accomplished by using the GAMESS 2012 software at M11/ktzvp level of theory in order to find their structural and electronic parameters. We show that the planarity of the molecules and the presence of the electron withdrawing group are advantages for its antimicrobial activity. Finally, we briefly present and discuss results on the processing of such compounds into thin films and hybrid structures by laser-assisted techniques, i.e. matrix-assisted pulsed laser evaporation (MAPLE) or laser-induced forward transfer (LIFT), to provide simple and environmental friendly, state-of-the-art solutions for antimicrobial/medical coatings and devices.

Research progress on the technique and materials for three-dimensional bio-printing

Three-dimensional (3D) bio-printing is a novel engineering technique by which the cells and support materials can be manufactured to a complex 3D structure. Compared with other 3D printing methods, 3D bio-printing should pay more attention to the biocompatible environment of the printing methods and the materials. Aimed at studying the feature of the 3D bio-printing, this paper mainly focuses on the current research state of 3D bio-printing, with the techniques and materials of the bio-printing especially emphasized. To introduce current printing methods, the inkjet method, extrusion method, stereolithography skill and laser-assisted technique are described. The printing precision, process, requirements and influence of all the techniques on cell status are compared. For introduction of the printing materials, the cross-link, biocompatibility and applications of common bio-printing materials are reviewed and compared. Most of the 3D bio-printing studies are being remained at the experimental stage up to now, so the review of 3D bio-printing could improve this technique for practical use, and it could also contribute to the further development of 3D bio-printing.

Nanotoxicity of nanodiamond in two and three dimensional liver models

Among classes of nanoparticles developed as drug carriers and theranostics, nanodiamond (ND) has been gaining an increasing attention owing to its biocompatibility, easy functionalisation and chemical stability. Although biocompatibility studies on nanodiamond produced by detonation technique have been explored extensively, NDs produced by laser assisted technique are yet to be investigated. Here, we present comparative study on toxicity of NDs in 2D and 3D liver models. Results suggest toxicity occurs on the 2D model at higher concentrations of NDs after long term exposure. However, cytotoxic effect was not observed in the case of the 3D model. In addition, alterations in nanomechanical properties of the cells after uptake of NDs were detected by a Lorentz contact resonance (LCR) spectroscopic study. Overall, the results indicate differences in the toxicity profile of NDs in 2D and 3D and long term toxicity studies on NDs produced by laser assisted technique must be done prior to any biomedical applications.

Structure-property relationships for Eu doped TiO2 thin films grown by a laser assisted technique from colloidal sols

Highly photoluminescent Eu doped TiO2 layers prepared by laser-based technique from colloidal sols.

Comparison of laser and power bleaching techniques in tooth color change.

BackgroundLaser-assisted bleaching uses laser beam to accelerate release of free radicals within the bleaching gel to decrease time of whitening procedure. The aim of this study was to compare the efficacy of power bleaching using Opalescence Xtra Boost® and laser bleaching technique using LaserSmile gel and diode laser as an activator in their tooth whitening capacity.Material and MethodsStudent t test showed that the laser bleaching group significantly outperformed the power bleaching group in changing ∆E (p=0.977).ResultsSimilarly, while comparing the groups in changing ∆L, the laser bleaching group indicated significantly superior results (p=0.953). Statistical data from student t test while comparing the groups in changing the parameter of yellowness indicated that samples in laser bleaching group underwent a more significant reduction than power-bleached samples (p=0.85). Correspondingly, changes in whiteness were statistically tested through student t test, showing that laser bleaching technique increased whiteness of the samples significantly more than those treated by power bleaching (p=0.965). The digital color evaluation data was in accordance with spectrophotometry and showed that laser bleaching outperformed power bleaching technique. Both techniques were able to increase whiteness and decrease yellowness ratio of the samples. ΔE decrease for laser bleaching and power bleaching groups were 3.05 and 1.67, respectively. Tooth color change in laser bleaching group was 1.88 times more than that of power bleaching group (p<0.001).ConclusionsIt could be concluded that under the conditions of this study, both laser-assisted and power bleaching techniques were capable of altering tooth color change, but laser bleaching was deemed a more efficient technique in this regard. Key words:Laser, power bleaching, tooth color introduction.

160 COMPARATIVE STUDY OF IN VITRO CULTURE MEDIA AND ASSISTED HATCHING TECHNIQUES ON MOUSE EMBRYOS

The in vitro culture media and assisted hatching techniques remain challenging obstacles to be utilised widely. Mechanical, chemical, enzymatic thinning, and laser-assisted techniques have been used previously but information is still lacking on its application in livestock. The aim of this study was to compare the effect of 2 in vitro culture media (Hamster F10 and TMC-199) and 4 (mechanical, chemical, enzymatic, and laser) assisted hatching techniques on blastocyst formation and hatching rate using murine embryos as a model. The C57/b and Balb/c breeds were raised until they reached maturity and bred naturally to produce F1 generation. The light in the breeding house was controlled at 14 h light and 10 h dark. Feed and water were provided ad libitum for the mice. Superovulation of females were stimulated using equine chorionic gonadotropin and human chorionic gonadotropin. The F1 generation was used for the collection of the 400 blastocysts and randomly allocated into 4 assisted hatching techniques. Blastocysts were paired into a group of 10 and replicated 4 times for each assisted hatching technique. The general linear model of SAS version 9.4 (SAS Institute Inc., Cary, NC, USA) was used to analyse the data. Assisted hatching techniques of laser, mechanical, enzymatic, and chemical yielded 46.9 ± 37.1, 51.1 ± 40.2, 39.1 ± 35.8, and 33.3 ± 4.5%, respectively, under in vitro culture of Hamster F10. The TCM-199, laser, mechanical, enzymatic, and chemical assisted hatching techniques yielded 56.3 ± 43.3, 52.6 ± 35.5, 49.2 ± 37.5, and 33.9 ± 35.5%, respectively, with a significant difference. There was no significant difference observed in assisted hatching techniques and Hamster F10 culture medium. However, the hatching rate of embryos for all techniques was higher when in vitro cultured in TCM than cultured in Hamster F10. Hatching rate of blastocysts increased from chemical, enzymatic, mechanical, and laser with response to Hamster F10 and TCM; thus, laser is a suitable assisted hatching technique with TCM-199.

Managing infected cardiovascular implantable electronic devices

AbstractThe number of cardiac implantable electronic device (CIED) implants is growing; unfortunately, the rate of device infections is also rising, outpacing the increase in device implantation and paralleling the complexity of current CIEDs and CIED recipients, incurring high morbidity and mortality, long hospital stays, and increased financial cost. For either pocket or lead infection, percutaneous complete removal of the infected device and lead system combined with prolonged antibiotic treatment is the standard approach to patient management. A variety of mechanical and/or laser‐assisted techniques and tools are employed with high success rates in experienced centers. Surgery is reserved for cases with very large vegetations, need for other concomitant cardiac surgery or for failed or complicated percutaneous approach. Following removal of an infected CIED, the need for reimplantation of a new device is individualized, although the timing is variable, mainly based on the absence of signs of continued infection. In general, CIED‐related infective endocarditis and the presence of comorbid conditions are associated with increased mortality. These and other important relevant issues of contemporary management of patients with infected CIEDs are herein reviewed.Answer questions and earn CME: https://wileyhealthlearning.com/Activity2/4596336/Activity.aspx

Structures and Properties of Laser-Assisted Cold-Sprayed Aluminum Coatings

In the cold spray process, solid particles impact on a surface with high kinetic energy, deform plastically and form a coating. This enables the formation of pure and dense coating structures. Even more, coating performance and deposition efficiency can be improved by assisting the process with a laser. Laser-assisted cold spraying (LACS) has shown its potential to improve coating properties compared with traditional cold spraying. In this study, coating quality improvement was obtained by using a co-axial laser spray (COLA) process which offers a new, cost-effective laser-assisted cold spray technique, for high-quality deposition and repair. In the COLA process, the sprayed surface is laser heated while particles hit the surface. This assists the better bonding between particles and substrate and leads to the formation of tight coating structures. This study focuses on the evaluation of the microstructural characteristics and mechanical properties (e.g., hardness and bond strength) of LACS metallic coatings.

Effects of boundary-layer separation controllers on a desktop fume hood

ABSTRACTA desktop fume hood installed with an innovative design of flow boundary-layer separation controllers on the leading edges of the side plates, work surface, and corners was developed and characterized for its flow and containment leakage characteristics. The geometric features of the developed desktop fume hood included a rearward offset suction slot, two side plates, two side-plate boundary-layer separation controllers on the leading edges of the side plates, a slanted surface on the leading edge of the work surface, and two small triangular plates on the upper left and right corners of the hood face. The flow characteristics were examined using the laser-assisted smoke flow visualization technique. The containment leakages were measured by the tracer gas (sulphur hexafluoride) detection method on the hood face plane with a mannequin installed in front of the hood. The results of flow visualization showed that the smoke dispersions induced by the boundary-layer separations on the leading edges of the side plates and work surface, as well as the three-dimensional complex flows on the upper-left and -right corners of the hood face, were effectively alleviated by the boundary-layer separation controllers. The results of the tracer gas detection method with a mannequin standing in front of the hood showed that the leakage levels were negligibly small (≤0.003 ppm) at low face velocities (≥0.19 m/s).

Lens-free laser nanopatterning of large-scale metal film areas with structured light for biosensing applications.

Pulsed laser nanotexturing of metal films represents an ultra-fast, high-performance and cost-effective processing technology for fabrication of various functional surfaces widely used in plasmonics, biosensing, and photovoltaics. However, this approach usually requires high-NA lenses to focus a laser beam onto a few-micron spot as well as a micropositioning platform to move this spot along the sample surface, which increases the cost of the produced functional surfaces and limits the performance of laser-assisted nanotexturing techniques. In this paper we report on a laser-assisted technology for the fabrication of large-scale nanotextured metal substrates. In our approach, speckle-modulated patterns obtained by passing nanosecond laser pulses through the simplest diffusive object were utilized to cover a thin gold film with closely packed micron-sized structures - nanojets, nanobumps and through holes - previously reported only for single-shot nanoablation with tightly focused laser beams. The presented easy-to-implement technology, being one of the simplest of ever reported, since it requires neither focusing lenses nor micropositioning platforms, was shown to provide a way to pattern millimeter-size areas with the nano-sized jets at an average recording density of 35∙103 nanostructures per square millimeter and an average recording speed of 4.5·103 nanostructures per pulse. The fabricated nanotextured Au substrates were shown to yield spatially uniform surface-enhanced fluorescence signals from the Rhodamine 6G organic dye with an averaged 5.3-fold enhancement factor as compared with non-treated Au surface.

Formation of a plano-convex micro-lens array in fused silica glass by using a CO2 laser-assisted reshaping technique

We report on fabricating high-fill-factor plano-convex spherical and square micro-lens arrays on fused silica glass surface using CO2 laser assisted reshaping technique. Initially, periodic micro-pillars have been encoded on the glass surface by means of a femtosecond laser beam. Afterwards, the micro-pillars are polished several times by irradiating a CO2 laser beam on top of the micro-pillars. Consequently, spherical micro-lens array with micro-lens size of 50 um x 50 um and square micro-lens array with micro-lens size of 100 um x 100 um are formed on fused silica glass surface. We also study the intensity distribution of light passed through the spherical micro-lens array engraved glass sample. The simulation result shows that, the focal length of the spherical micro-lens array is 35 um. Furthermore, we investigate the optical properties of the micro-lens array engraved glass samples. The proposed CO2 laser based reshaping technique is simple and fast that shows promises in fabrication arrays of smooth micro-lenses in various transparent materials.

The Friction Reducing Effect of Square-Shaped Surface Textures under Lubricated Line-Contacts—An Experimental Study

Surface texturing has been shown to be an effective modification approach for improving tribological performance. This study examined the friction reduction effect generated by square dimples of different sizes and geometries. Dimples were fabricated on the surface of ASP2023 steel plates using femtosecond laser-assisted surface texturing techniques, and reciprocating sliding line contact tests were carried out on a Plint TE77 tribometer using a smooth 52100 bearing steel roller and textured ASP2023 steel plates. The tribological characterization of the friction properties indicated that the textured samples had significantly lowered the friction coefficient in both boundary (15% improvement) and mixed lubrication regimes (13% improvement). Moreover, the high data sampling rate results indicated that the dimples work as lubricant reservoirs in the boundary lubrication regime.

THE EFFECT OF ASSISTED HATCHING IN FROZEN-THAWED EMBRYO TRANSFER CYCLES

Background: Laser assisted hatching technique based on the hypothesis to make an artificial hole on zona pellucida (ZP) that can help embryo hatching out of ZP easily. This technique has been shown to increase implantation and pregnancy rates in women of advanced age, in women with recurrent implantation failure and following the transfer of frozen–thawed embryos. This study described the outcome of frozen–thawed embryo transfers with laser assisted hatching (LAH), which is one of the safest method in nowadays. Purpose: To assess the effect of assisted hatching technique on the clinical outcomes in vitrified-warmed transfer cycles. Method: A total of 65 thawed-transfer cycles with 153 thawed-embryos undertaken within a 12-month period were analysed, Assisted hatching with laser zona thinning was performed with one-quarter of the zona pellucida circumference. The overall thawed-embryos (day 3) were kept in culture overnight. Patient were prepared the suitable endometrium and transferred embryos advantageously. Results: In which, having the rate of survival embryos were 143 occupying 94.3%, the percentage of grade 1 and 2 embryos occupied 55.9% and 29,3% respectively, and that were enrolled LAH before transfering of frozen–thawed embryos. The average transferred embryos were 2.4±0.8, The rate of implantation per transferred embryos and per transferred embryos cycles was 19.5% and 43.1% respectively. The rate of clinical pregnancies per embryo transfer cycles occupied 33.8% with percentage of early miscarriages (biochemical pregnancies and early clinical miscarriages) was 12.3%. The rate of ongoing pregnancies was 30.8% and multiple pregnancies was low just 12.3%. This result was equal or higher than other researchs in embryos transfer had or no LAH. Conclusion: LAH contributed to stable frozen–thawed embryos transfer effectiveness. Key words: Laser assisted hatching, frozen–thawed embryos transfer, zona pellucida (ZP)