Effects Of Nanosecond Research Articles

Deuterium–deuterium fusion in nanowire plasma driven with a nanosecond high-energy laser

Investigating the enhancement of the interaction between laser and plasma is crucial for fundamental and applied physics research studies based on laser-induced acceleration and nuclear reactions. The improvement of energy conversion efficiency resulting in increasing reaction yields has been extensively studied by the interaction of femtosecond (fs) or picosecond (ps) lasers with nanowire targets. However, the effects of nanosecond (ns) lasers interacting with nanowire targets on energy absorption and production yield remain unknown. To address this issue, we conducted a deuterium–deuterium fusion experiment based on the collision of two plasmas induced by the interaction of the kilo-Joule-level nanosecond laser with nanowire targets. The experimental results of neutron detection indicate that the yields of nanowire targets remain at the same level as those of planar targets. We have used the counter-streaming collisionless plasma model to perform a numerical analysis of the output of nuclear reaction products at the center-of-mass energy (Ec.m.) values between 10 and 30 keV, and the calculation results are in good agreement with the experimental results. In addition, a magneto-hydrodynamic numerical simulation was also performed. It shows that the critical density of the target’s surface, which forms on the picosecond time scale, blocks the absorption of laser energy with nanosecond pulse length. Consequently, both our experimental and simulation results indicate that the enhancement factor is limited when a target with a spatial period less than µm is used in conjunction with a ns laser. Therefore, additional research is highly desirable to develop a target structure that can improve the efficiency of energy conversion between the laser and the target.

Effect of nanosecond- and microsecond-pulse Er,Cr:YSGG laser ablation on dentin shear bond strength of universal adhesives.

The study aimed to evaluate the bond strength of universal adhesives to dentin after Er,Cr:YSGG laser irradiation with nanosecond-domain and microsecond-domain pulses. Eighty extracted caries-free, sound human molars were divided into eight groups. The enamel was removed until the dentin occlusal flat dentin surface was exposed. Etch-and-rinse followed by adhesive was applied to group 1, and a self-etch adhesive was applied to group 2. Er,Cr:YSGG laser (3mJ, 100Hz, 100ns), (3mJ, 100Hz, 150μs), and (20mJ, 100Hz, 150μs) were applied to groups 3-4, 5-6, and 7-8, respectively. The laser preparation was followed by self-etch adhesives or adhesives treatment. When the composite resin had been built up on the samples, the shear bond strength was tested, and the data were statistically analyzed using analysis of variance (ANOVA). Groups prepared with nanosecond-pulse laser showed significantly higher bond strength values than the microsecond-pulse laser groups and self-etch mode group, and the SEM photographs also showed more dentinal tubules and no damage in the ablation area. The shear bond strength of long pulse laser ablated was comparable to that of self-etching system when it was combined with a self-etch adhesive at low energy, but higher energy laser degraded shear bond strength. The pulse width of Er,Cr:YSGG laser affects the bond strength, nanosecond pulses of laser irradiation without water cooling can enhance bond strength, but microsecond pulses of laser cannot enhance bond strength.

Current Approaches in Surface Processing of Biomedical Alloys; Laser Processes

One of the branches of science where great developments are taking place today is biomaterials. Biomaterials are natural or artificial materials that can be used for the replacement of diseased or damaged organs or tissues, and in some cases they can be used for purposes such as correcting body functions or increasing the functionality of organs, replacing a living system or working in contact with living tissue. The known material types that are metallic, ceramic, polymeric and composite materials are each used as biomaterials. Among these, metallic biomaterials which are especially prominent in terms of their mechanical properties are widely used in many biomedical applications such as orthopedic implants, fracture treatment screws, braces and dental implants among the application areas of metallic biomaterials and biomedical alloys. As in all biomaterials, the most important factor determining the success of biomedical alloys is their biocompatibility. Since their first interaction with the biological systems occurs on the material surface, surface treatments are commonly used methods for improving the biocompatibility of biomedical alloys. Among these methods, the laser surface structuring method is a promising, contamination-free, non-contact and environmentally friendly surface treatment technique to modify the surface properties of materials in the biomedical industry. Nanosecond and femtosecond laser irradiation applications emerge at this point and allow to change the surface properties of different biomaterial alloys. Within the scope of this article, the changes in the surface properties of biomaterials with the effect of nanosecond and femtosecond laser irradiations, applications with different laser techniques were examined and the results were compiled.

纳秒激光诱导表面微纳结构对锆基金属玻璃生物兼容性的影响

纳秒激光诱导表面微纳结构对锆基金属玻璃生物兼容性的影响

Effect of nanosecond and femtosecond pulse laser on the formation of WS2 nanostructures and field emission characteristics

The pulse laser ablation is a simple and direct method used for the generation of nanostructures in liquid environment. In this paper, formation of tungsten sulfide [Formula: see text] nanostructures has been carried out using nanosecond (ns) and femtosecond (fs) laser ablation with ablation time 120 min. In addition, the field emission studies were performed of the prepared sample. The characterization techniques such as the transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-visible spectroscopy have been used to confirm the surface morphology as well as structural details. It is observed that the laser pulse regime plays a vital role on the size reduction of [Formula: see text] nanostructure. The X-ray spectra reveal the formation of [Formula: see text] nanoparticles for ns laser ablation, while [Formula: see text] nanosheets for fs laser ablation. The TEM images indicate that the transformation of [Formula: see text] microsheet into nanosheet of the size about 15–200 nm for the sample treated with ns laser and fs laser ablation. Also, the results clearly shows the improvement in the field emission characteristics for laser ablated [Formula: see text] nanosheets. The enhanced field emission characteristics is attributed to the formation and separation of few layer [Formula: see text] nanosheets. The [Formula: see text] nanostructures may have great potential for the applications in optoelectronic devices.

The Effect of Nanosecond, High-Voltage Electric Pulses on the Shape and Permeability of Polymersome GUVs.

Polymersomes, vesicles composed of block copolymers, are promising candidates as membrane alternatives and functional containers, e.g., as potential carriers for functional molecules because of their stability and tunable membrane properties. In the scope of possible use for membrane protein delivery to cells by electrofusion, we investigated the cytotoxicity of such polymersomes as well as the effects of nanosecond electric pulses with variable repetition rate on the shape and permeability of polymersomes in buffers with different conductivities. The polymersomes did not show cytotoxic effects to CHO and B16-F1 cells in vitro in concentrations up to 250µg/mL (for 48h) or 1.35mg/mL (for 60min), which renders them suitable for interacting with living cells. We observed a significant effect of the pulse repetition rate on electrodeformation of the polymersomes. The electrodeformation was most pronounced in low conductivity buffer, which is favorable for performing electrofusion with cells. However, despite more pronounced deformation at higher pulse repetition rate, the electroporation performance of polymersomes was unaffected and remained in similar ranges both at 10Hz and 10kHz. This phenomenon is possibly due to the higher stability and rigidity of polymer vesicles, compared to liposomes, and can serve as an advantage (or disadvantage) depending on the aim in employing polymersomes such as stable membrane alternative architectures or drug vehicles.

Abstract 5387: Exploring effects of nanosecond and microsecond pulsed electric field ablation in a rat orthotopic hepatocellular carcinoma model

Abstract Hepatocellular carcinoma (HCC) is the third most common cancer in the world. A diagnosis of HCC carries a guarded prognosis, especially when metastasis is documented. Reliable, curative treatment for very early, early, and intermediate stages is still an inconsistent ideal. Nanosecond (ns), or microsecond (μs) pulsed electric fields (PEFs) that produce irreversible electroporation (IRE) could be used to ablate local tumor masses through minimal invasive or open surgery delivery. Both nsPEFs and μsPEFs induce permanent permeabilization of cells resulting in cell death without any thermal effect. NsPEFs can also impact intracellular organelles and induce apoptosis. Previous studies indicated under certain condition, there was a protective tumor response following nsPEFs treatment in mouse subcutaneous HCC model. In these studies, we specifically test the efficacy of nsPEFs and μsPEFs in an orthotopic HCC rat tumor model. N1S1 cells stably transfected with luciferase were used to generate tumors. Orthotropic insertion of transfected N1S1 HCC cells in Sprague Dawley rat livers was used as the model. Different pulses numbers, rise times and pulse durations were applied. The effect on treated tumor tissue suggests that a single treatment of 500 or 1000 100ns pulses with either slow (50ns) or fast (10ns) rise times and 50 kV/cm can eliminate HCC tumors. Continuous delivery of eighty 100μs microsecond pulses at 2.5 kV/cm dramatically reverses lesion enlargement. 1000 pulses of 100 ns PEFs with fast rise times provoke an innate immune response. Immune responses in this orthotopic HCC model are still under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5387. doi:1538-7445.AM2012-5387

Fluorescence microscopy imaging of electroperturbation in mammalian cells

We report the design, integration, and validation of a fluorescence microscopy system for imaging of electroperturbation--the effects of nanosecond, megavolt-per-meter pulsed electric fields on biological cells and tissues. Such effects have potential applications in cancer therapy, gene regulation, and biophysical research by noninvasively disrupting intracellular compartments and inducing apoptosis in malignant cells. As the primary observing platform, an epifluorescence microscope integrating a nanosecond high-voltage pulser and a micrometer electrode chamber enable in situ imaging of the intracellular processes triggered by high electric fields. Using specific fluorescence molecular probes, the dynamic biological responses of Jurkat T lymphocytes to nanosecond electric pulses (nanoelectropulses) are studied with this system, including calcium bursts, the polarized translocation of phosphatidylserine (PS), and nuclear enlargement and chromatin/DNA structural changes.

Effect of Nanosecond Electromagnetic Pulses on the Properties of Matter

Effect of Nanosecond Electromagnetic Pulses on the Properties of Matter