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Antibacterial activity of ZnO nanoparticles fabricated using laser ablation in solution technique
摘要： The zinc oxide (ZnO) nanoparticles have been produced by using laser ablation in solution technique, resulting nanoparticles with hexagonal wurtzite structure and the size range of 20 – 50 nm. The optical characterization has predicted the nanoparticles band gap at least 3.16 eV. The ZnO nanoparticles were employed as an antibacterial agent for the growth of Escherichia coli (E. coli), and it shows a great potential. Total plate count (TPC) analysis was conducted by applying the ZnO nanoparticles with different concentration of 5%, 10%, 15%, 20%, 25% and 30% (portion of bacteria medium). The 5% concentration could reduce more than half of the E. coli population after 24 hours incubation time. There was no living bacteria detected for 20%, 25% and 30% ZnO concentration.
关键词： ZnO nanoparticles,laser ablation,antibacterial activity,Escherichia coli
更新于2025-09-23 15:19:57
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Preparation and characterization of organic nanoparticles by laser ablation in liquids technique and their biological activity
摘要： The laser ablation in liquids (LAL) method was used for the synthesis of organic colloidal nanoparticles in deionized water as a liquid medium. The effect of variations of the lens-target distance and laser wavelength on the size, structure, and morphology of the nanoparticles was studied. A target of bulk organic bifenthrin compound (agricultural insecticide) was elaborated for the ablation process. By means of ultraviolet-visible (UV–vis) absorption spectroscopy, the characteristic absorbance spectra were analyzed, con?rming the presence of nanoparticles. Furthermore, the absorbance was related to the nanoparticles concentration. Structural characterization and size determination were carried out by transmission electron microscopy (TEM). The crystalline structure of the nanoparticles was studied by comparing the interplanar distance of the nanoparticles determined by high-resolution transmission electron microscopy (HR-TEM) with the interplanar distances of the bulk material observed by x-ray diffraction (XRD). The study of chemical composition was carried out by gas chromatography coupled to mass spectrometry (GC-MS). The nanoparticles sizes varied between 3 and 20 nm, with a narrow size distribution. According to the results, both the size and structure of the nanoparticles are mainly determined by the incident energy density on the target, whilst wavelength affects morphology. On the other hand, the preliminary biological tests of the nanoparticles carried out with Drosophila melanogaster, showed an enhanced insecticide activity at signi?cant lower concentrations in comparison with doses used with bulk bifenthrin.
关键词： organic nanostructures,nanoparticles,nano-insecticide,laser ablation,bifenthrin
更新于2025-09-23 15:19:57
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Study of thermal conductivity of synthesized Al2O3-water nanofluid by pulsed laser ablation in liquid
摘要： In the present study, Aluminum oxide (Al2O3) nanoparticles dispersed water based nanofluids were prepared via laser ablation in liquid method. Al2O3 nanoparticles were synthesized in deionized water using a nanosecond Nd-YAG pulsed laser operating at 1064 nm. The structural, optical and morphological characterizations of the produced nanofluids were performed. Thermal properties of the prepared samples were evaluated through thermal conductivity measurements which were carried out at various nanoparticles concentration and at temperatures ranging from 25 °C to 45 °C. Morphological analysis by transmission electron microscopy revealed spherically shaped Al2O3 nanoparticles with an average size of 9 nm. Moreover, the results indicated that the thermal conductivity of Al2O3-water nanofluid was improved as compared to the pure water. The increase in temperature and nanoparticles concentration leads to higher thermal conductivity of nanofluids. It was found that the thermal conductivity enhancement was around 8.6% at nanoparticles volume fraction of 0.7 vol.% and temperature of 45°C. This work proved the possibilities of fabricating Al2O3-water nanofluid with enhanced thermal conductivity via laser ablation in liquid medium without the use of hazardous chemicals and vacuum conditions. Therefore, the synthesized nanofluids have great potential to be applied in medium temperature applications.
关键词： thermal conductivity,nanofluids,temperature,Al2O3 nanoparticles,laser ablation
更新于2025-09-23 15:19:57
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Novel Use of Nona??Invasive Devices and Microbiopsies to Assess Facial Skin Rejuvenation Following Laser Treatment
摘要： Patient‐reported outcomes and blinded observer rating scales are subjective and unreliable but are extensively utilized to evaluate cosmetic office‐based treatments, including ablative lasers. This study aims to assess the practicality of using non‐invasive and minimally invasive methods for objective skin assessment following a skin rejuvenation treatment. Twelve patients received a single 1,470/2,940 nm laser treatment for facial rejuvenation. Assessments were performed before treatment, and 7 days, 3 weeks, and 3 months post‐treatment. Images were taken with the VISIA Skin Analysis System to measure wrinkles, textures, pores, ultraviolet (UV) spots, brown spots, red areas, and porphyrins. Other non‐invasive skin measurements—high‐resolution ultrasonography, optical coherence tomography, transepidermal water loss and BTC 2000—were used to measure epidermal/dermal thickness, blood flow, surface roughness, wrinkle depth, attenuation coefficient, elasticity, viscoelasticity. Microbiopsies (0.33 mm in diameter or the equivalent of a 23‐gauge needle) were collected for histology and gene expression of tissue rejuvenation. Significant improvement in facial skin aesthetics after laser treatment was recorded in UV spots, brown spots and pores after 3 weeks and in UV spots and brown spots after 3 months. The dermal attenuation coefficient decreased significantly at 3 weeks, while blood flow 0.5 to 0.7 mm below the skin surface increased significantly between 5 days and 3 weeks following treatment. Epidermal hyaluronic acid expression assessed by immunostaining and expression of inflammatory genes were elevated at 7 days post‐treatment compared with untreated or 3 months post‐treatment. There were no statistically significant changes in collagen or elastin‐related genes between groups at the studied parameters. Non‐invasive devices can be effectively used to provide objective measurements of skin structure, pigmentation, blood flow, and elasticity to assess the efficacy of facial skin rejuvenation treatments. Furthermore, microbiopsies can objectively evaluate facial skin rejuvenation without scarring. Using non‐invasive skin imaging, a single treatment with the 1,470/2,940 nm laser was observed to be effective in improving skin appearance after 3 months, namely in reducing UV spots and brown spots, without significant changes in the tissue at the molecular level, as assessed by microbiopsy.
关键词： non‐invasive,laser ablation,microbiopsy,skin biopsy,skin rejuvenation,skin imaging
更新于2025-09-23 15:19:57
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Determination of the isotopic composition of enriched materials using laser ablation molecular isotopic spectrometry: partial least squares and multivariate curve resolution for the determination of 15N content in enriched urea
摘要： A quantitative analytical method based on laser ablation molecular isotopic spectrometry (LAMIS) and multivariate analysis was developed and evaluated for the determination of the isotopic composition of enriched materials. The method consists preparing a concentrated solution of the enriched material, using small quantities of a sample (125 mg), and ensuring the economic efficiency of the analysis. Standard solutions of known isotopic contents are prepared by employing mixtures of urea highly enriched in 15N and urea of natural isotopic ratio and analyzed by mass spectrometry. A small volume (30 μL) of these solutions is delivered to a filter paper disc (3 cm diameter). After drying, the disc, offering a homogeneously distributed analyte, is presented to a LAMIS equipment to acquire the vibronic emission spectra containing information about the isotopologues of interest. To illustrate the proposed method, the content of 15N is determined in enriched samples of urea. In this case, each spectrum is normalized by the intensity of emission of the CN isotopologues for the electronic (Δν = 0) emission band at 387.1 nm, ensuring better accuracy. Selected regions and single wavelengths of the vibronic emission spectrum (Δν = + 1 or ? 1) related to CN species were employed to construct multivariate partial least squares (PLS) and univariate regression models to predict the isotopic content of new samples. Besides, the LAMIS data set was evaluated by multivariate curve resolution (MCR) algorithm. The best MCR and PLS models presented similar results regarding the accuracy to determine 15N content in enriched urea. MCR is capable of identifying spectral interferences and minimizing its effect. The results show that the proposed method based on LAMIS and PLS or MCR multivariate analysis can determine the 15N content in the range 5–50% with a root mean square error of prediction (RMSEP) respectively equal to 0.5 or 0.7% (m/m) in comparison with reference results obtained by mass spectrometry.
关键词： 15N determination in enriched urea,Laser ablation molecular isotopic spectrometry (LAMIS),Isotopic composition of enriched materials,Partial least squares,Multivariate regression,Multivariate curve resolution (MCR)
更新于2025-09-23 15:19:57
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Stable nano-silver colloid production via Laser Ablation Synthesis in Solution (LASiS) under laminar recirculatory flow
摘要： As nanomaterials find applications in an increasingly diverse range of fields such as wastewater treatment, biotechnology and flexible electronics, the demand for nanomaterials with specific properties has increased. This increase is coupled with an increasing emphasis on nanomaterials with highly specific properties for specialised applications. Industrially, nanomaterials are produced via wet-chemical techniques which employ the use of solvents and reagents which are environmentally harmful. As we move forward with the use of nanomaterials, the ability to produce nanomaterials in a sustainable manner has become a topic of great significance. Towards this end, Laser Ablation Synthesis in Solution (LASiS) is a physical production technique capable of producing tailored nanomaterial colloids in a sustainable manner. These colloids are produced by ablating a solid target immersed in a solvent using a laser. Typically, LASiS is conducted in a batch process and in small volumes limiting commercial viability. To overcome this, there has been a move towards the use of continuous production via LASiS using flow systems. This allows an increase in nanomaterial yield, resulting in colloid concentrations approaching those of commercial colloids. This work investigates a new production technique incorporating a laminar recirculatory flow system to produce stable high concentration nano-silver colloids.
关键词： silver,Nanoparticle,laser ablation synthesis in solution,size-quenching
更新于2025-09-23 15:19:57
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Formation of periodic superhydrophilic microstructures by infrared nanosecond laser processing of single-crystal silicon
摘要： The evolution of the morphology and composition of the single-crystal silicon surface irradiated by infrared and visible nanosecond laser pulses is investigated as a function of processing parameters (laser fluence, irradiation spot size, the number of pulses, background gas pressure and composition). Two types of periodic surface microstructures are obtained with IR (1064 nm) laser pulses in a narrow fluence range of 3-6 J/cm2. At a relatively low number of laser pulses applied, a grid of cleavage cracks is produced within the irradiation spot along the crystal orientation. With further Si irradiation, periodic microhillocks are formed in the nodes of the crack grid. Silicon surface with such microhillocks exhibits superhydrophilic properties which are retained during prolonged storage in air. The cracks are produced in any environment (including vacuum) but the microhillocks are observed only in the presence of oxygen. No periodic structures were observed with visible (532 nm) laser pulses. Mechanisms of nanosecond laser-induced periodic microstructure formation on silicon are discussed.
关键词： oxidation,superhydrophilicity,silicon,periodic microstructures,Nanosecond laser ablation,damage threshold
更新于2025-09-23 15:19:57
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Highly realistic simulation for robot-assisted hypothalamic hamartoma real-time MRI-guided laser interstitial thermal therapy (LITT)
摘要： Purpose Real-time MRI-guided laser interstitial thermal therapy (LITT) is a challenging procedure due to its technical complexity, as well as the need for efficient multidisciplinary teamwork and transfer of an anesthetized patient between operating room (OR) and magnetic resonance (MR). A highly realistic simulation was developed to design the safest process before being applied to real patients. In this report, authors address the description of the methodology used for this simulation and its purposefulness. Methods The entire image planning, anesthetic, and surgical process were performed on a modified pediatric simulation mannequin with a brain made of medical grade silicone including a hypothalamic hamartoma. Preoperative CT and MR were acquired. Stereotactic insertion of the optical fiber was assisted by the Neuromate? stereotactic robot. Laser ablation was performed with the Medtronic Visualase? MRI-guided system in a 3T Phillips Ingenia? MR scanner. All the stages of the process, participants, and equipment were the same as planned for a real surgery. Results No critical errors were found in the process design that prevented the procedure from being performed with adequate safety. Specific proposals for team positioning and interaction in patient transfers and in MR room were validated. Some specific elements that could improve safety were identified. Conclusion Highly realistic simulation has been an extremely useful tool for safely planning LITT, because professionals were able to take actions in the workflow based not on ideas but on lived experiences. It contributed definitively to build a well-coordinated surgical team that worked safely and more efficiently.
关键词： Robotic surgery,Patient safety,Pediatric epilepsy surgery,Risk management,Laser ablation
更新于2025-09-23 15:19:57
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Polyvinyl Alcohol/Silver nanoparticles film prepared via pulsed laser ablation: An eco-friendly nano-catalyst for 4-nitrophenol degradation
摘要： This work attempts to introduce an eco-friendly nano-catalyst PVA/AgNPs portable film for 4-nitrophenol degradation. Silver nanoparticles (AgNPs) doped Polyvinyl Alcohol (PVA) film has been synthesized via one-potential pulsed laser ablation in liquids (PLAL) technique. The structural, optical, and morphological studies of the synthesized PVA/AgNPs nanocomposite film have been characterized by different techniques such as; XRD, FT-IR, UVeVis, PL, FE-SEM, and EDAX. From X-ray diffraction technique (XRD), it is approved that the synthesized PVA/AgNPs film is polycrystalline with cubic structure form. From UVeVisible spectroscopy, the energy band gap was determined by using tauc relation, which was found to be 3.7eV for direct transition. From morphological study, FE-SEM photos of the synthesized PVA/AgNPs film show the homogeneous distributed spherical-like shape of silver nanoparticles in PVA. The qualitative and semi-quantitative elemental analysis of the prepared samples via EDAX technique confirmed the embedding of the silver nanoparticles in the PVA structure. The amazing performance of the prepared PVA/AgNPs film in catalytic degradation activity for 4-nitrophenol reduction has been investigated, which lead to degrade 93% of 4-nitrrophenol in 25 min.
关键词： Silver nanoparticles,Catalytic degradation,PVA,Pulsed laser ablation,Nitrophenols
更新于2025-09-23 15:19:57
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Silver and copper oxide nanoparticles-decorated graphene oxide via pulsed laser ablation technique: Preparation, characterization, and photoactivated antibacterial activity
摘要： Graphene oxide, silver and copper oxide nanoparticles display photoactivated antibacterial behavior owing to their ability to generate charge carriers via light exposure. In this work, silver nanoparticles (AgNPs) and copper oxide nanoparticles (CuONPs) were embedded through graphene oxide (GO) using laser ablation technique. The microstructural behavior of the synthesized compositions has been investigated via XRD and TEM. The optical properties were studied by (UV–Vis), while the antibacterial properties were investigated in addition to the cell viability towards normal cell line (HFB4) in vitro. The antibacterial activity of GO was enhanced significantly with addition nanoparticles; by meaning, the inhibition zone enlarged from 5.4 mm with pure GO to be around 11.2 mm against E. coli with contribution of CuONPs. This trend of enhancement suggests that GO could be a great platform for different kinds of photo-activated antibacterial to be recommended for versatile biomedical applications.
关键词： CuO,Ag,Pulsed laser ablation,Graphene oxide,Antibacterial activity,Bacterial resistance
更新于2025-09-23 15:19:57