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We consider the possibility of improving the superhigh-power laser pulse to superponderomotive electrons energy conversion efficiency by using porous targets of near-critical density. We report the results of numerical simulations based on the typical parameters of laser pulses of the PEARL laser facility built on the principles of parametric chirped pulse amplification (OPCPA). An original scheme for producing a controllable prepulse based on the use of a pump laser switched to a two-pulse regime is discussed. The prepulse is required to homogenise the submicron inhomogeneities of a porous target. Simulations show a significant increase in the laser-to-electron energy conversion efficiency in comparison with solid-state and gas targets. This interaction regime can be used to improve the efficiency of a broad class of laser-driven secondary radiation sources, such as a betatron source, bremsstrahlung, neutron source, etc.

Photoluminescence piezospectroscopy (PLPS) is a laser-based noncontact and nondestructive stress measurement technique but has not been studied extensively in the field of civil structural health monitoring. Using the PLPS technique, the stress level can be measured by emitting a laser source onto a target’s surface. In this study, PLPS was attempted for noncontact stress measurement of concrete. Alumina is one of the chemical components of Portland cement, and is a highly sensitive material for PLPS. Therefore, alumina in concrete can be used as a passive stress sensor by PLPS. To investigate the spectral detectability at different alumina rates, cement mortar specimens were prepared with increasing concentrations of additional alumina. It was determined that spectral detectability increases with increasing alumina concentration. Then, uniaxial compression tests were conducted to investigate the relationship between stress level and spectral shifts. It was ascertained that compressive stress and spectral shifts have a negative linear relationship. Then, the effective piezospectroscopic coefficients were calculated to be − 0.1574 cm−1/MPa and − 0.1468 cm−1/MPa for the R1 and R2 bands, respectively. The experimental results reveal that application of PLPS to concrete can provide essential information for structural health monitoring and allow for preventive measures to be taken before collapse of cement structures.

Endocorporeal laser lithotripsy (ELL) is currently the gold standard for the treatment of renal stones during retrograde intra-renal surgery (RIRS). The newly-authorised thulium fibre laser (Tm-Fibre) in now evaluated as a holmium:yttrium-aluminium-garnet (Ho:YAG) laser alternative, which is the most well-known laser source for ELL. This update aimed to present the fundamentals of pulsed lasers for EEL [technology, period, pulse characteristic (rate, duration, energy, shape), peak power, average power], and the available lithotripsy modes for both Tm-Fibre and Ho:YAG lasers.

This paper analyses the metal transfer process dynamics to assess how weld pool, laser source and filler wire interact to establish a stable and smooth deposition. The investigation led to the definition of suitable manufacturing settings and process parameters. Satisfactory geometrical and microstructural properties were achieved for a 15-layer titanium alloy wall.

Objective: The study assesses the safety and efficacy of a 675-nm laser source on melasma. Background: Melasma is a frequent acquired skin disease defined by the presence of hyperpigmented macules ...

Direct metal deposition is a free-form metal deposition technique used to generate near-net-shape 3D components with applications ranging from automobile, aerospace, and biomedical sectors, etc. The process has attracted research interest in industries due of its vast potential and advantages over other metal additive manufacturing processes. Innovations in laser technology have facilitated the advancements in the direct metal deposition technique, which leads to the need to explore the potential and influence of the lasers in part quality and accuracy. To produce defect-free parts with superior mechanical properties and functional features, the process should to be better understood in connection with application of the appropriate laser source. Therefore, this article aims to elaborate on the significance of continuous-wave and pulsed-wave lasers concerning the process and characteristics of parts produced. The review will conclude by summarising the capabilities and applications of continuous-wave and pulsed-wave lasers in the direct metal deposition. Therefore, this review would aid the manufacturing industries, research, and development sector to better understand influence of laser sources in achieving defect-free products.

The micro manufacturing of ceramic components is technologically challenging especially when complex shapes and micro features are required. A hybrid manufacturing chain is developed for non-sintered(green) blanks machined using sequentially a cutting tool and a laser source. During the preparation of the green blank, a binder is added to the powder to improve compaction. The amount of binder can affect the quality of the machining. The goal of this paper is to study its influence on the material removal rate and the surface quality with both technologies and to determine the optimal proportion for using this hybrid machining.

Biophysics subject covers multiple fields of physics and biology. In this research the effect of some parameters of diode laser has been experimented with ants (Camponotus consobrinus) which includes the effect on its external shape, as well as the percentage of the killing rate obtained as a result of laser radiation at a wavelength (532 nm) with power (200 mW), at distances: (10, 12, and 14 cm) between laser source and the insect, and exposure times (10, 15 and 20 sec) for each distance. The obtained results showed an increase in the rate of ant killing, as well as an increase in deformations where the distance decreased and laser exposure time increased. These results were recorded after time periods after laser treatment, which are as follows: (12, 24, 48 and 72 h). The thermal diffusion within the tissues resulting from laser radiation causes increased death rates due to damage of internal structures.

In laser-assisted machining (LAM), the laser source is focused on the workpiece as a thermal source and locally increases the workpiece temperature and makes the material soft ahead of the cutting tool so using this method, the machining forces are reduced, which causes improving the surface quality and cutting tool life. Machinability of advanced hard materials is significantly low and conventional methods do not work effectively. Therefore, utilizing an advanced method is inevitable. The product life and performance of complex parts of the leading industry depends on surface integrity. In this work, the surface integrity features including microhardness, grain size and surface roughness (Ra) and also the maximum cutting temperature were investigated experimentally in LAM of Ti-6Al-4V. According to the results, cutting speed has inverse effect on the effectiveness of LAM process because with increasing speed (15 to 63 m/min), temperature decreases (524 °C to 359 °C) and surface roughness increases (0.57 to 0.71 μm). Enhancing depth of cut and feed has direct effect on the process temperature, grain size, microhardness and surface roughness.

The goal of the present work is to increase the detectivity of hyperspectral imaging systems, deployed on airborne marine search and rescue platforms (SAR), also the increase of the probability for camouflaged target detection and recognition through optimization of image quality. Hence, water column spectral characteristics will be simulated, bringing into consideration the effect of both air layer and plankton layer. This experimental simulation is based on hyperspectral imaging of camouflaged dummy targets of different shapes in a special aquarium designed for this purpose, where an argon laser source was used as multi-spectral line target illuminator and three different bottom backgrounds were tested.

Illegal production of potentially hazardous narcotics as well as various psychotropic drugs is being carried out in the neighbouring countries and international market which is causing narco-terrorism a global havoc. Compared with traditional/natural drugs the synthetic drugs are more smuggled nowadays. Because of the vulnerability of the borders to drug trafficking, India has increased surveillance at borders and coasts and thus has tackled the problem to some extent. Authors developing a Narcotic drug sensor (point sensor) for detection and identification of Narcotic drugs based on Laser Induced Fluorescence more specifically Synchronous Fluorescence Spectroscopy in an effort. Some narcotic samples viz. Caffeine, Quinine and Tramadol were considered for the study. The fluorescence spectrum was studied using our own laboratory-based sensor incorporating charge coupled device-based Spectrometer and Laser source (266 nm wavelength) and commercial system from ‘Horiba Scientific’ incorporating Photomultiplier tube and Xe lamp source.

Objective: This study evaluates the efficacy and safety of a new 675 nm laser source system on melasma. Background: Melasma is an acquired circumscribed hyperpigmented disorder that has a negative ...

In many chemical reactions, the transformation from reactants to products is mediated by transient intermediate complexes. For gas-phase reactions involving molecules with a few atoms, these complexes typically live on the order of 10 ps or less before dissociating, and are therefore rarely influenced by external processes. Here, we demonstrate that the transient intermediate complex K2Rb2*, formed from collisions between ultracold KRb molecules, undergoes rapid photo-excitation in the presence of a continuous-wave laser source at 1,064 nm, a wavelength commonly used to confine ultracold molecules. These excitations are facilitated by the exceptionally long lifetime of the complex under ultracold conditions. Indeed, by monitoring the change in the complex population after the sudden removal of the excitation light, we directly measure the lifetime of the complex to be 360 ± 30 ns, in agreement with our calculations based on the Rice–Ramsperger–Kassel–Marcus (RRKM) statistical theory. Our results shed light on the origin of the two-body loss widely observed in ultracold molecule experiments. Additionally, the long complex lifetime, coupled with the observed photo-excitation pathway, opens up the possibility to spectroscopically probe the structure of the complex with high resolution, thus elucidating the reaction dynamics. A transient intermediate complex in a chemical reaction—formed from collisions between molecules with a few atoms—is observed under ultracold conditions. Its lifetime can be directly measured after suppression of the photo-excitation process.

Acne scarring represents a common problem that negatively impacts patients’ quality of life. Different types of treatments are currently available for this dermatological condition. This study evaluates the efficacy of a new 675-nm laser source system on acne scars with the use of established parameters that guarantee minimum pain and the absence of side effects such as hyperpigmentation, hypopigmentation, and blistering. A total of 24 subjects (all women, aged 21–42 years), with Fitzpatrick skin types I–IV and facial acne scars, were treated with three sessions of a 675-nm laser system. Efficacy of treatment was evaluated using the Goodman and Baron’s quantitative grading scale before and 3 months after the last treatment. All 24 patients treated with this new 675-nm laser had significant improvement of acne scars according to Goodman and Baron’s Quantitative Global Acne Scarring Grading System. No side effect has been observed except some minor erythematous reactions in three patients. The 675-nm laser system we used appears to be effective and well-tolerated in patients with acne scars, and it involves a simple post-treatment management.

Purpose This study aims to discuss the effect of carbon fiber on the electric-respone of shape memory epoxy property. Epoxy (EP) is a typical excellent thermosetting shape memory polymer (SMP). To enrich the shape memory epoxy (SMEP) responsive mode, the carbon fiber fabric-reinforced SMEP composites were prepared, and the mechanical properties and the electric- and light-responsive shape memory effect of the composites were investigated and confirmed. Design/methodology/approach The carbon fiber fabric/SMEP composites were prepared via a dipping method. The carbon fiber fabric was dipped into the waterborne epoxy emulsion and dried at room temperature and then post-cured in the oven at 120 °C for 2 h. The mechanical properties and the multi-responsive shape memory properties of the composites were tested and confirmed via tensile test instrument, DC electrical source and near-infrared (NIR) laser source control system. Findings The carbon fiber fabric/SMEP composites showed excellent electric- and light-responsive shape memory effect. Research limitations/implications High performance and multi-responsive shape memory materials have always been the goal of the scientists. Carbon fiber fabric and SMEP both consist of a good reputation in the field of composites, and the combination of both would set a solid foundation for getting a high performance and multi-responsive shape memory effect materials, which will enrich the responsive mode and broaden the application of SMEP. Originality/value Multi-responsive SMEP composites were prepared from waterborne epoxy and carbon fiber fabric.

Taiwan-Turkey Science Summit on Translation of Cells, Nanomaterials and Signaling Molecules into Regenerative Medicine -- APR 01-03, 2018 -- Ankara, TURKEY /0000-0002-5463-8355; Akcan, Ramazan/0000-0002-4100-9488; Tamer, Ugur/0000-0001-9989-6123; Yildirim, Mahmut Serif/0000-0001-8861-9016; Ilhan, Hasan/0000-0002-4475-1629 WOS:000566495700038 PubMed: 32178510 Background: Heroin can be detected and quantified by certain analytical methods, however, forensic professionals and criminal laboratories study for cheaper and faster detection tools. Surface-enhanced Raman spectroscopy (SERS) rises as a possible alternative tool with its widening application spectra. There are few studies regarding Raman and SERS spectra of heroin and its metabolites, which are unfortunately controversial. In this study, we compared five different surfaces in order to find out more efficient Raman-active substrate for opiate detection and rapid quantification of heroin and its metabolites in saliva. Materials and methods: Morphine standard material was used to identify proper surface for SERS analysis of opiates. Heroin and its metabolites (morphine, morphine-3-beta-glucuronide and 6-monoacetyl morphine) were calibrated between 50 ppb and 500 ppm and quantified on AuNRs with signal enhancement of silver colloids in saliva. Raman microscope with a 785-nm laser source was used. Results and Conclusion: Obtained results showed that heroin and its metabolites can be detected and quantified in saliva samples using a SERS-based system. Additionally, the present study revealed that synergetic effect of a specific gold nano-surface with ability controlling liquid motion and silver nanoparticles increase band numbers and intensities. Therefore, we suggest a fast, accurate and cost-effective method to detect and quantify heroin in biological fluids. Hacettepe UniversityHacettepe University [THD-2018-17241] This work was supported financially by Hacettepe University (Grant Number: THD-2018-17241). This article is based on studies of PhD thesis of Ramazan AKCAN in Bioengineering Department of Graduate School of Science and Engineering. This study was presented in Taiwan-Turkey Science Summit that was held in Ankara, Turkey, on 1-4 April 2018. Authors would to acknowledge Assoc. Prof. Gokhan DEMIREL for his technical support and material supply support.

We revisit the reductive coupling of p-nitrothiophenol (NTP) to form dimercaptoazobenzene (DMAB), herein monitored through gap-mode tip-enhanced Raman spectroscopy (TERS) and nanoimaging. We employ a plasmonic Au probe (100 nm diameter at its apex) illuminated with a 633 nm laser source (50 μW/μm2 at the sample position) to image an NTP-coated faceted silver nanoparticle (∼70 nm diameter). A detailed analysis of the recorded spectra reveals that anionic NTP species contribute to the recorded spectral images, in addition to the more thoroughly described DMAB product. Notably, the signatures of the anions are more pronounced than those of the DMAB product under our present experimental conditions. Our results thus demonstrate that anions and their spectral signatures must be considered in the analysis of plasmon-enhanced optical spectra and images.

We report a simple means to build a model atomic force microscope (AFM) using 3D printing of thermoplastic materials that are commercially available. The model has many of the key parts of an actual AFM including a z-axis stage, an AFM head with a cantilever assembly, and a laser source that reflects off of the back of the cantilever. Using a magnet attached to the tip of the cantilever and a metal sample, this model AFM enables acquisition of force–distance profiles with characteristic snap-in, pull-off, separate, and contact regions. The model AFM was designed, printed, and used by first- and second-year undergraduate students. Through completion of this project, students learned scientific instrument design and construction via 3D printing and obtained first-hand practice in the measurement of force–distance profiles and the elastic constants of cantilevers. The open design of the model can easily accommodate additional capabilities in which students are interested, e.g., topographical scanning and using cantilevers made from different materials.

The $ C^2\Pi $ - $ X^2\Pi $ (0, 0) band of AgO has been reinvestigated by laser induced fluorescence spectroscopy with a spectral resolution of $ \sim $ 0.02 cm $ ^{-1} $ . The AgO molecules are produced by discharging a gas mixture of O $ _2 $ /Ar with silver needle electrodes in a supersonic jet expansion. By employing a home-made narrowband single longitude mode optical parametric oscillator (SLM-OPO) as the laser source, high-resolution spectra of the $ C^2\Pi $ - $ X^2\Pi $ (0, 0) band have been recorded for both $ ^{107} $ Ag $ ^{16} $ O and $ ^{109} $ Ag $ ^{16} $ O isotopologues. The spectroscopic constants of the $ C^2\Pi $ state are consequently determined, with the $ ^{109} $ Ag $ ^{16} $ O one being reported for the first time. The nature of the spin-orbit coupling effect in the $ C^2\Pi $ state is proposed to be due to state mixing with the nearby repulsive $ ^{4}\Sigma^{-} $ and $ ^{4}\Pi $ states.

We present images of microholes drilled in diamond using a homemade femtosecond Yb : KGW laser. We use a femtosecond laser source emitting pulses with a duration of 230 fs at a wavelength of 1030 nm, the focusing spot size amounting to 8.9 μm. The effect of the pulse energy and the number of pulses on the microhole geometry (hole diameter, circularity, taper angle, and drilling quality) is evaluated. The obtained results demonstrate the feasibility of drilling of hourglass-shaped holes in a diamond sample, which have similar diameters at the hole entrance (92 μm) and exit (95 μm), but a much smaller diameter (28 μm) at a certain waist section inside the hole.

It's a huge challenge to develop effective nanosystems that combine the capabilities of diagnoses and therapies together for colon cancer in the clinic. Herein, we constructed a far-red absorbing phototheranostic nanosystem (FR-H2S) based on the thiolytic reaction of a dinitrophenyl modified phototheranostic prodrug and over-expressed H2S in colon cancer sites for precise imaging-guided phototherapy. FR-H2S with a BODIPY core not only could work as an imaging probe for diagnosis but also act as a phototherapeutic agent for cancer treatment under a single FR laser source (650 nm). FR-H2S exhibited a gradually enhanced fluorescence emission for precise diagnosis of H2S-rich colon tumor sites. After entering tumor cells, FR-H2S could generate abundant 1O2 and heat for phototherapies timely by using the same laser source (650 nm). We believe that this precise imaging-guided phototheranostic nanosystem could provide a promising approach to colon cancer with minimal damage.

Weakly coupled multicore fiber (WC-MCF) is promising for use in short-reach fiber telecommunication systems in the near future. Intercore crosstalk (XT) plays an important role in WC-MCF-based short-reach intensity-modulation/direct-detection (IM/DD) systems, because XT can significantly degrade system performance. For the first time, the combined effect of intercore XT and the frequency offset between optical carriers, which is defined as the carrier beating impairment (CBI), is measured and characterized by experiments and numerical simulations. The experimental results show that the CBI causes large fluctuations in the signal-to-noise ratio (SNR) with a normally tolerable XT level. Such SNR fluctuations can additionally reduce the system’s XT tolerance (at worst 1-dB SNR degradation) by as much as 20 dB for 4-level pulse amplitude modulation (PAM-4) transmission. The simulation results show that the CBI is mainly affected by the specific properties of the laser source and the modulation depth of the transmitted signals. These results suggest that the XT should be designed to be much smaller for WC-MCF-based short-reach IM/DD systems when there is the CBI.