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Chiral quantum dots (QDs) are promising materials applied in many areas, such as chiral molecular recognition and spin selective filter for charge transport, and can be prepared by facile ligand exchange approaches. However, ligand exchange leads to an increase in surface defects and reduces the efficiencies of radiative recombination and charge transport, which restricts further applications. Here, we investigate the light-induced photoluminescence (PL) enhancement in chiral L- and D-cysteine CdSe QD thin films, providing a strategy to increase the PL. The PL intensity of chiral CdSe QD films can be significantly enhanced over 100 times by continuous UV laser irradiation, indicating a strong passivation of surface defects upon laser irradiation. From the comparative measurements of the PL intensity evolutions in vacuum, dry oxygen, air, and humid nitrogen atmospheres, we conclude that the mechanism of PL enhancement is photo-induced surface passivation with the assistance of water molecules. [ABSTRACT FROM AUTHOR]

The N–H photodissociation dynamics of the pyridinyl radical upon continuous excitation to the optically bright, first excited ππ* electronic state by an ultra-violet (UV) laser pulse has been investigated within the mathematical framework of optimal control theory. The genetic algorithm (GA) is employed as the optimization protocol. We considered a three-state and three-mode model Hamiltonian, which includes the reaction coordinate, R (a1 symmetry); the coupling coordinates (namely, out-of-plane bending coordinate of the hydrogen atom of azine group), Θ (b1 symmetry); and the wagging mode, Q9 (a2 symmetry). The three electronic states are the ground, ππ*, and πσ* states. The πσ* state crosses both the ground state and the ππ* state, and it is a repulsive state on which N–H dissociation occurs upon photoexcitation. Different vibrational wave functions along the coupling coordinates, Θ and Q9, of the ground electronic state are used as the initial condition for solving the time-dependent Schrödinger equation. The optimal UV laser pulse is designed by applying the GA, which maximizes the dissociation yield. We obtained over 95% dissociation yield through the πσ* asymptote using the optimal pulse of a time duration of ∼30 000 a.u. (∼725.66 fs). [ABSTRACT FROM AUTHOR]

There is an ongoing debate on the apparent depletion of sulfur in the interstellar medium (ISM) compared to its universal abundance; therefore, the investigation of sulfurous compounds at low temperatures is of utmost importance. This work aims to study thioacetamide, H3C–C(=S)–NH2, in low-temperature inert Ar and para-H2 matrices by IR spectroscopy. The samples have been exposed to various sources of irradiation, such as Lyman-α or laser UV photons as well as energetic electrons. Using different host materials enabled assessing the matrix's impact on precursor decomposition. The response of the molecule to different types of irradiation has also been evaluated. The existence of three main decomposition channels were deduced: formation of (i) CH3, CH4, and HNCS; (ii) H2S and H2C=C=NH; and (iii) NH3 and H2C=C=S. The H3C–CN and H3C–NC isomers of H2C=C=NH could also be identified. Secondary products such as HNC and HCN were also detected in the quantum solid para-H2 in contrast to the more rigid Ar matrix. The listed decomposition products have been observed in the ISM, with the exception of H2C=C=NH and H3C–NC. The results point to the potential sensitivity of the precursor molecule to energetic radiation in space environments. Finally, the findings of this work will serve as a foundation for future irradiation experiments using the astrochemically more relevant pure thioacetamide ice. [ABSTRACT FROM AUTHOR]

The precise determination of the bond dissociation energy of N2 is crucial for thermochemistry database and theoretical calculations. However, there has been ongoing debate regarding its exact value. In this study, we used the velocity map imaging method combined with an extreme ultraviolet laser to measure the threshold fragment yield (TFY) spectra of N2 in the N(2D) + N(2D) photodissociation channels. By integrating the signals within a small circular area on the fragment velocity map images, we were able to obtain TFY spectra at nine different dissociation thresholds. These spectra are rotational state-resolved for the N2(J″) molecules and spin–orbit state-resolved for the dissociation channels involving N(2D) fragments. By employing the Wigner threshold law to simulate the TFY spectra and conducting statistical analysis on the comprehensive dataset, we determined the N2 bond dissociation energy to be 78 691.09 ± 0.15 cm−1. This work now places N2 among the few diatomic molecules with bond dissociation energies measured at sub-wavenumber precision. [ABSTRACT FROM AUTHOR]

We have studied the aging-induced degradation effect and the related mechanism of blue and ultraviolet (UV) laser diodes (LDs). First of all, the F parameter value, leakage current, and yellow luminescence intensity of LDs all increase after 24 h of the aging process, indicating that one of the reasons for the degradation of UV LDs may be the increase of the non-radiative recombination center in the material. Second, irreversible damage may be found on the front cavity surface of the UV and blue LDs. Due to the large UV photon energy, water molecules in the environment atmosphere are ionized to form OH− ions, which combine with dust in air to form SiO2 sediments and then attach to the front cavity surface. In addition, a large photon energy may cause damage to the anti-reflection film on the front cavity surface and lead to a too-high local temperature near the cavity surface, resulting in molten Ga droplets. Both sediment and the precipitation of molten GaN on the cavity surface will directly affect the function of the front cavity surface and the output power of the LD. In order to improve the reliability of the GaN-based UV LDs, it is necessary to reduce the density of material defects, select more stable coating materials on cavity facets, and improve the sealing property of the device package. [ABSTRACT FROM AUTHOR]

This work describes the plume chemistry of laser-ablated carbon–carbon (C–C) composite samples in vacuum, a range of air pressures, and in pure oxygen. Time-resolved spectra were measured from a plasma plume generated by laser-ablation at 248 nm. The focus of this work was on the detection of three chemical species, C2, CN, and CO in pressures from near vacuum (10−7 Torr) to air at atmospheric pressure (760 Torr). Emission from atomic carbon C I was predominant at 10−7 Torr, while molecular C2 Swan Band emission was observed at 10−7 Torr, at all air pressures, as well as in pure oxygen. Emission from the CN violet bands was observed only when ablating in air, but not in vacuum or pure O2, indicating that CN was the product of a chemical reaction between an ablated carbon species and N2 present in air, and not intrinsically present in the C–C composite targets. High-resolution emission spectra from C2 and CN were measured and fitted to vibrational and rotational temperatures. Time-resolved emission measurements of both these molecules were used to estimate their respective velocities as a function of pressure. No emission from excited state CO could be detected from 180–900 nm, even in pure O2. However, neutral and ground state CO and CO2 were both detected by measuring FTIR absorption spectra following the ablation of a composite target at 248 nm, in dry air at atmospheric pressure. The HITRAN database was used to calculate the concentrations of CO and CO2 produced per laser pulse. [ABSTRACT FROM AUTHOR]

Laser-produced plasma is a promising compact light source applicable in a broad range of wavelengths. We performed a spectroscopic analysis and plasma characterization of the laser-produced plasma of Al, Fe, Cu, and Inconel alloy (Ni/Cr/Fe) to explore their potential applications in the far-ultraviolet (FUV) region where these methods are yet widely exploited. The emission spectrum from each target exhibited a characteristic spectral profile over the wavelength range from 120 to 250 nm. These results were well reproduced by spectral simulations, providing detailed information on the plasma. We also developed a dedicated parabolic mirror that successfully collimated the plasma radiation into beam with an intensity enhanced by a factor of ∼ 35. Our study demonstrated the generation of collimated FUV radiation with an intensity of a 10 7 photons/pulse/1% bandwidth as a potent laboratory-size light source for various applications. [ABSTRACT FROM AUTHOR]

Thermal gradient‐driven fluid motion, also known as thermal convection, is a common and significant phenomenon in nature. The utilization of localized thermal gradients to induce convection has emerged as a competitive approach in microfluidic chips. This technique enables the long‐distance transportation of substances under the influence of low‐power lasers. In this paper, an innovative optofluidic micro‐platform is presented that possesses a simple structure, easy operation, and excellent expandability. A UV nanosecond laser is utilized to create a high photothermal conversion region (HPCR) within the carbon nanotube‐doped PDMS substrate. Subsequently, the HPCR is subjected to irradiation for generating localized thermal gradients in the microfluidic chip. This resulted in Rayleigh–Bernard convection formation and facilitated long‐range transport and control of fluids and particles. Under low‐power laser irradiation, particles can be transported at speeds up to 0.18 mm s−1. In addition, the optofluidic platform shows significant potential for a range of functionalities, including fluid mixing and material sorting. The methodology described here allows for the rapid integration of new functionalities into existing chips while maintaining cost effectiveness and efficiency. This technique holds great promise for expanding the use of microfluidic devices in diverse fields, including chemistry, health sciences, materials science, and biomedicine. [ABSTRACT FROM AUTHOR]

In this work, we present studies on the effect of laser wavelengths on the laser-induced plasma characterization using a femtosecond (fs) ytterbium-doped potassium-gadolinium tungstate (Yb:KGW) laser. Plasma plumes of copper, steel, ceramics, and glass samples were induced using a multiple shot of 200 fs laser pulses with 1030 nm and 343 nm wavelengths at fixed laser fluence (10.5 J / cm 2) and analyzed using the laser-induced breakdown spectroscopy (LIBS) technique. Time-resolved fs-LIBS measurements were performed on the same set of samples and under the same experimental conditions. For the calculation of plasma parameters, the set of spectral lines of Cu(I) (for copper sample), Fe(I) (for steel sample), and Ca(I), K(I) (for glass and ceramics samples) were observed. The plasma electron temperature and density were evaluated from the Boltzmann plots and Stark-broadening profiles of the plasma spectral lines, assuming the local thermodynamic equilibrium condition. Time-resolved plasma temperature and electron density for fs-LIBS using ultraviolet (UV) and infrared (IR) laser wavelengths were analyzed and no significant dependence on fs laser wavelength was observed for any of the samples. However, for all samples the signal-to-noise ratio (SNR) significantly increased using UV laser radiation: copper (∼ 100 %), steel (∼ 300 %), glass (∼ 400 %), and ceramics (∼ 40 %). Therefore, by using a fs UV laser wavelength for laser-induced breakdown spectroscopy experiments, for certain materials the SNR and at the same time the limit of detection can be significantly enhanced. [ABSTRACT FROM AUTHOR]

The traditional aviary decontamination process involves farmers applying pesticides to the aviary's ground. These agricultural defenses are easily dispersed in the air, making the farmers susceptible to chronic diseases related to recurrent exposure. Industry 5.0 raises new pillars of research and innovation in transitioning to more sustainable, human-centric, and resilient companies. Based on these concepts, this paper presents a new aviary decontamination process that uses IoT and a robotic platform coupled with ozonizer (O3) and ultraviolet light (UVL). These clean technologies can successfully decontaminate poultry farms against pathogenic microorganisms, insects, and mites. Also, they can degrade toxic compounds used to control living organisms. This new decontamination process uses physicochemical information from the poultry litter through sensors installed in the environment, which allows accurate and safe disinfection. Different experimental tests were conducted to construct the system. First, tests related to measuring soil moisture, temperature, and pH were carried out, establishing the range of use and the confidence interval of the measurements. The robot's navigation uses a back-and-forth motion that parallels the aviary's longest side because it reduces the number of turns, reducing energy consumption. This task becomes more accessible because of the aviaries' standardized geometry. Furthermore, the prototype was tested in a real aviary to confirm the innovation, safety, and effectiveness of the proposal. Tests have shown that the UV + ozone combination is sufficient to disinfect this environment. [ABSTRACT FROM AUTHOR]

Strongly differing static dipole moments of the trans and cis isomers of photochromic azobenzene allow for optical switching of the work function of azobenzene-functionalized self-assembled monolayers (SAMs). We apply these properties in a fundamental experiment to manipulate the area size of the switched SAM. Azobenzene molecules were excited by ultraviolet laser illumination, and the transient isomerization profile of the SAM was spatially resolved recording photoemission electron microscopy images. Thereby, we demonstrate the spatial tuning of the SAM's work function and discuss the role of the laser spot profile in generating sharp edges or gradual changes of the work function. [ABSTRACT FROM AUTHOR]

• Samples of thin gold and black resin were found in an ancient Egyptian tomb. • LIBS is used to analyze black resin and gold in embalming remains. • Spectroscopic results revealed butemen and not pure gold. • EDX measurements of the same samples validated the LIBS results. Laser-induced breakdown spectroscopy (LIBS) has recently been considered one of archaeology's most preferred analytical techniques because of its simplicity; it does not need sample preparation, is fast, is a quasi-nondestructive analytical technique, and is cost-effective. Besides, LIBS can perform stratigraphic measurements, which are of significant interest in cultural heritage samples. Such pros facilitate utilizing LIBS in situ, e.g., in museums and excavation sites. In the present work, LIBS has been used to analyze black resin remains and gold fragments used in mummification and collected from the Ptahemwia tomb in the vicinity of Djoser's Step Pyramid at Sakkara. The IR (1064 nm) and the UV (355 nm) laser wavelengths have been used in the LIBS measurements. The results revealed both samples' emission line intensity dependence on the laser wavelength. In this regard, elements such as Na, Ca, Mo, and CN (molecular band) for black resin and Au, Ag, and Cu for gold samples were detected as significant elements. It has been found that the detection sensitivity achieved by the LIBS technique was higher when using the UV laser. This is crucial in detecting rare earth elements REE (Y, La) and/or minor elements (Nb, Zr) in the samples under study. Furthermore, the energy-dispersive X-ray (EDX) analysis has been used to validate the LIBS results for the same samples. In agreement with what is reported in the literature, the LIBS and the EDX spectroscopic results showed that the black resin investigated in the present study is bitumen in its composition. [Display omitted] [ABSTRACT FROM AUTHOR]

Lead in any food is harmful even at low concentrations. In this study, a direct and highly sensitive lead analysis technique was developed for wheat flour using laser-induced fluorescence combined with laser-induced breakdown spectroscopy. Wheat flour was pressed into small pellets and ablated by a low-energy ultraviolet 266-nm laser. A tunable dye laser constructed in our laboratory was used to resonantly excite the lead. The optimized interpulse time delay was 400 ns. A calibration curve was constructed and the detection limit for lead was 73.8 ppb. This method could be used to directly and sensitively analyze wheat flour for trace concentrations of lead. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) technology has recently seen increased utilization due to its versatility in using functional materials, offering a new pathway for next-generation conformal electronics in the smart sensor field. However, the limited availability of polymer-based ultraviolet (UV)-curable materials with enhanced piezoelectric properties necessitates the development of a tailorable process suitable for 3D printing. This paper investigates the structural, thermal, rheological, mechanical, and piezoelectric properties of a newly developed sensor resin material. The polymer resin is based on polyvinylidene fluoride (PVDF) as a matrix, mixed with constituents enabling UV curability, and boron nitride nanotubes (BNNTs) are added to form a nanocomposite resin. The results demonstrate the successful micro-scale printability of the developed polymer and nanocomposite resins using a liquid crystal display (LCD)-based 3D printer. Additionally, incorporating BNNTs into the polymer matrix enhanced the piezoelectric properties, with an increase in the voltage response by up to 50.13%. This work provides new insights for the development of 3D printable flexible sensor devices and energy harvesting systems. [ABSTRACT FROM AUTHOR]

The injection and leakage of charge carriers have a significant impact on the optoelectronic performance of GaN-based lasers. In order to improve the limitation of the laser on charge carriers, a slope-shape hole-barrier layer (HBL) and electron-barrier layer (EBL) structure are proposed for near-UV (NUV) GaN-based lasers. We used Crosslight LASTIP for the simulation and theoretical analysis of the energy bands of HBL and EBL. Our simulations suggest that the energy bands of slope-shape HBL and EBL structures are modulated, which could effectively suppress carrier leakage, improve carrier injection efficiency, increase stimulated radiation recombination rate in quantum wells, reduce the threshold current, improve optical field distribution, and, ultimately, improve laser output power. Therefore, using slope-shape HBL and EBL structures can achieve the superior electrical and optical performance of lasers. [ABSTRACT FROM AUTHOR]

To elucidate whether it is feasible to use porcine eyes from scalded, abattoir-acquired animals for refractive femtosecond laser research. An infrared laser (FS 200) and an ultraviolet laser (prototype version) were tested for their applicability on scalded pig eyes. Fifty porcine eyes were divided into two equally-sized groups and assigned to either the infrared or the ultraviolet laser. Both laser groups were comprised of five subgroups of n = 5 eyes each. Group A: non-scalded eyes (negative control); group B: eyes taken from tunnel-scalded animals; group C1: eyes taken from tank-scalded animals without opaque corneal lesion; group C2: eyes taken from animals with opaque corneal lesion; group D: eyes scalded in toto in the laboratory (positive control). In each group the lasers were employed to create a stromal flap. The quality of the laser cuts and the resulting flap beds, as well as of the porcine corneas themselves, was examined by anterior segment optical coherence tomography and scanning electron microscopy. All scalded specimens exhibited substantial corneal swelling, most pronounced in group C2. After ultraviolet laser application, the tank- and tunnel-scalded samples displayed marked irregularities and an increased degree of surface roughness in the flap beds. After infrared laser application, this was only the case in the tank-scalded specimens. It is not recommended to use eyes taken from scalded pigs for ultraviolet femtosecond laser experiments. For infrared femtosecond lasers, eyes taken from tunnel-scalded animals may represent an acceptable alternative, if non-scalded eyes are not available. [ABSTRACT FROM AUTHOR]

The advanced research on bright 13.5 nm extreme ultraviolet (EUV) light sources with low debris is of crucial importance for the semiconductor industry. The scheme of laser produced colliding plasma holds the potential to significantly improve the conversion efficiency (CE) from the laser energy to the required EUV light sources. A pulsed Nd:YAG laser beam was split into two beams using a polarizing cube and focused on a planar Sn target surface at a distance of 2.5 mm to generate two colliding plasmas. It was found that the optical radiation intensity of the stagnation layer generated in the colliding plasmas region was much higher than that of a single-pulse plasma under the same laser energy. Furthermore, the stagnation layer could exist for a longer time with a higher optical radiation intensity, which meant that the formation of the stagnation layer effectively converted the ion kinetic energy into optical radiation energy. The time-of-flight (TOF) ion signal of the colliding plasma exhibited a much narrower distribution compared to the seed plasma. At the same laser energy, the ion kinetic energy of the colliding plasma was lower than that of the single-pulse plasma. The TOF peak voltage and total charge showed a stronger angular dependence for the colliding plasma. At high laser energy, the colliding plasma could significantly reduce the ion's kinetic energy without changing the CE of the EUV. [ABSTRACT FROM AUTHOR]

Spectroscopic analysis of trivalent praseodymium (Pr+3) and neodymium (Nd+3) ions have received very much interest and reveals good fluorescence efficiency in visible and near IR (NIR) region. Cadmium sulfide (CdS) nanomaterial sample doped with Pr+3 and Nd+3 ions are synthesized at room temperature by simple chemical precipitation method. The synthesized sample has been characterized by powder X‐ray diffraction studies, scanning electron microscopy, transmission electron microscopy, and energy dispersive X‐ray spectra. Absorption spectra of CdS:Nd3+ and CdS:Pr3+ nanoparticles have been recorded at room temperature. Various parameters such as interplanar spacing, micro strain, dislocation density, distortion parameter, and particle size of nanomaterial are computed. TEM and XRD analysis reveal the spherical structure of the CdS:Nd3+ and CdS:Pr3+ nanoparticles in the prepared samples. Energy interaction parameters of the CdS:Nd3+ and CdS:Pr3+ nanoparticles are computed using UV‐visible absorption spectrum. Actually, CdS nanoparticle amplifies the luminescence intensity of Pr+3, Nd+3 ions by up conversion processes. So energy transfer can be observed from CdS nanoparticles doped with Pr+3, Nd+3 ions. Therefore, the use of pump sources and diode lasers in the UV range can be used to excite these samples to work as lasers. CdS:Nd3+ and CdS:Pr3+ nanoparticles find potential application as a window material for hetero‐junction solar cell, light emitting diodes (LED), biological sensors, address decoders, gas detectors, opto‐electronic devices, etc. CdS nanomaterials are also used as pigment in paints and in engineered plastic due to their good thermal stability. [ABSTRACT FROM AUTHOR]

Structural characterization of neutral water clusters is crucial to understanding the structures and properties of water, but it has been proven to be a challenging experimental target due to the difficulty in size selection. Here, we report the size-specific infrared spectra of confinement-free neutral water nonamer (H2O)9 based on threshold photoionization, using a tunable vacuum ultraviolet free-electron laser. Distinct OH stretch vibrational fundamentals in the 3200–3350 cm−1 region are observed, providing unique spectral signatures for the formation of an unprecedented (H2O)9 structure evolved by adding a ninth water molecule onto a hydrogen bond-unbroken edge of the (H2O)8 octamer with D2d symmetry. This nonamer structure coexists with the five previously identified structures that can be viewed as derived by inserting a ninth water molecule into a hydrogen bond-broken edge of the D2d/S4 octamer. These findings provide key microscopic information for systematic understanding of the formation and growth mechanism of dynamical hydrogen-bonding networks that are responsible for the structure and properties of condensed-phase water. [ABSTRACT FROM AUTHOR]

Chemical modifications of proteins induced by ambient ozone (O 3) and nitrogen oxides (NO x) are of public health concerns due to their potential to trigger respiratory diseases. The laboratory and environmental exposure systems have been widely used to investigate their relevant mechanism in the atmosphere. Using bovine serum albumin (BSA) as a model protein, we evaluated the two systems and aimed to reduce the uncertainties of both the reactants and products in the corresponding kinetic study. In the laboratory simulation system, the generated gaseous pollutants showed negligible losses. Ten layers of BSA were coated on the flow tube with protein extraction recovery of 87.4%. For environmental exposure experiment, quartz fiber filter was selected as the upper filter with low gaseous O 3 (8.0%) and NO 2 (1.7%) losses, and cellulose acetate filter was appropriate for the lower filter with protein extraction efficiency of 95.2%. The protein degradation process was observed without the exposure to atmospheric oxidants and contributed to the loss of protein monomer mass fractions, while environmental factors (e.g., molecular oxygen and ultraviolet) may cause greater protein monomer losses. Based on the evaluation, the study exemplarily applied the two systems to protein modification and both showed that O 3 promotes the protein oligomerization and nitration, while increased temperature can accelerate the oligomerization and increased relative humidity can inhibit the nitration in the environmental exposure samples. The developed laboratory and environmental systems are suitable for studying protein modifications formed under different atmospheric conditions. A combination of the two will further reveal the actual mechanism of protein modifications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we investigated both spontaneous and stimulated whispering gallery mode (WGM) emissions of 2 mol. % Li+-doped ZnO (Li-ZnO) microspheres with different sizes under 325 and 488 nm wavelength laser excitations, respectively. It was found that all the microspheres exhibit stimulated emissions under a visible laser excitation source of 488 nm wavelength after the threshold pumping power. Thereafter, we studied the dependence of threshold pumping power on the size of microresonators to achieve stimulated emissions by individual microspheres. Furthermore, two microspheres (MS2 and MS3) are excited via a 325 nm UV laser, and surprisingly, the WGM peaks of higher intensity are observed in the visible rather than in the UV spectral region. We expected that most of the emissions are achieved via defect states transitions instead of inter-band transitions in the microresonators. It was found that WGMs in each microsphere exhibit a linear spectral shift of 3–5 nm with increasing pumping power of 488 nm excitation laser source. We believe that these proposed microspheres can be utilized effectively as WGM-based visible lasers and sensors. [ABSTRACT FROM AUTHOR]

Metal photocathodes are widely utilized as electron sources for particle accelerators for their ease of use, high durability, and fast response time. However, the high work function (WF) and low quantum efficiency (QE) typically observed in metals necessitate the use of high power deep UV lasers. Metal oxide ultra-thin films on metals offer a route to photocathodes with a lower WF and improved QE while maintaining photocathode durability and response time. We show how the photocathode performance of an Ag(100) single crystal is enhanced by the addition of an ultra-thin MgO film. The film growth and WF reduction of 1 eV are characterized, and the QE and mean transverse energy (MTE) are measured as a function of illumination wavelength. An eightfold increase of QE is achieved at 266 nm without adding to MTE through additional surface roughness, and the resistance of the photocathode to O 2 gas is greatly improved. [ABSTRACT FROM AUTHOR]

Rationale: Characterization of Regolith And Trace Economic Resources (CRATER), an Orbitrap™‐based laser desorption mass spectrometry instrument designed to conduct high‐precision, spatially resolved analyses of planetary materials, is capable of answering outstanding science questions about the Moon's formation and the subsequent processes that have modified its (sub)surface. Methods: Here, we describe the baseline design of the CRATER flight model, which requires <20 000 cm3 volume, <10 kg mass, and <60 W peak power. The analytical capabilities and performance metrics of a prototype that meets the full functionality of the flight model are demonstrated. Results: The instrument comprises a high‐power, solid‐state, pulsed ultraviolet (213 nm) laser source to ablate the surface of the lunar sample, a custom ion optical interface to accelerate and collimate the ions produced at the ablation site, and an Orbitrap mass analyzer capable of discriminating competing isobars via ultrahigh mass resolution and high mass accuracy. The CRATER instrument can measure elemental and isotopic abundances and characterize the organic content of lunar surface samples, as well as identify economically valuable resources for future exploration. Conclusion: An engineering test unit of the flight model is currently in development to serve as a pathfinder for near‐term mission opportunities. [ABSTRACT FROM AUTHOR]

Polyether ether ketone (PEEK) has excellent chemical stability, x-ray transmittance, and elastic modulus close to human cortical bone, which can effectively reduce the stress shielding effect. Therefore, PEEK can be used as a commonly used medical bone implant material to repair damaged bones. However, due to its low surface free energy, PEEK has a certain degree of biological inertness. Surface modification methods are urgently needed to improve this problem. Laser surface texturing is expected to improve the biological inertia of PEEK materials. In this study, an ultraviolet laser with a wavelength of 355 nm was used to construct textures on the surface of PEEK materials. By biomimetic design on the surface of PEEK materials, textures similar in depth and width to the surface topography of natural bones were processed. We explore the specific improvement of corrugated texture, single line texture, and orthogonal texture on PEEK material performance, aiming at improving the service performance of PEEK material and creating conditions for better service of PEEK material in vivo. Through the evaluation of PEEK surface contact angle, friction and wear properties, and biocompatibility, the research results show that laser surface texture treatment can improve many service properties of PEEK materials. [ABSTRACT FROM AUTHOR]

We utilize a novel, high-power, tunable, continuous wave (CW) deep UV laser to measure resonance Raman spectra of phenolate solutions with high signalto-noise ratios (SNR). In UV resonance Raman (UVRR), increased coupling of the excitation light with a chromophore can transfer molecules into excited states that cause increased heating and photochemistry. Deep UV lasers have traditionally utilized high peak powers to enable efficient single-pass nonlinear conversion from visible into near infrared light. Nonlinear phenomena such as the formation of transient radical species, Raman saturation, thermal heating, and dielectric breakdown can introduce extraneous light sources that can complicate the interpretation of the Raman spectrum. Dielectric breakdown can increase the baseline, increase noise, and sometimes saturate the detector, preventing Raman detection. Spontaneous Raman scattering intensities should scale linearly with the excitation light intensity. However, this linear behavior does not always occur with pulsed laser excitation. This occurs because stimulated Raman scattering can cause a superlinear intensity response, or transient absorption can cause sublinear intensity responses. CW laser excitation excites samples with electric fields that are much lower than typical pulsed laser excitation. This eliminates the nonlinear responses. The geometry of our new CW laser enables high gain in the harmonic generation cavities that achieve high harmonic generation efficiencies. Average power in the deep UV is >30 mW for wavelengths as short as 206 nm. In the work here, we demonstrate that CW excitation is ideal for resonance Raman measurements in general to reduce spectral complexity. [ABSTRACT FROM AUTHOR]

Photochemical reactions of salicylhydroxamic acid were induced using tunable UV laser radiation followed by FTIR spectroscopy. Four pairs of co-products were experimentally found to appear in the photolysis: C6H4(OH)NCO⋯H2O (1), C6H4(OH)C(O)N⋯H2O (2), C6H4(OH)2⋯HNCO (3), and C6H4(OH)NHOH⋯CO (4). The comparison of the theoretical spectra with the experimental ones allowed us to determine the structures of the complexes formed in the matrices. The mechanisms of the reaction channels leading to the formation of the photoproducts were proposed. It was concluded that the first step in the formation of the complexes (1), (2), and (3) was the scission of the N-O bond, whereas the creation of complex (4) was due to cleavage of the C-N bond. [ABSTRACT FROM AUTHOR]

The development of high-performance optically induced voltage materials represents a significant challenge within the realm of optical detection. The constraints posed by low induced voltage and extended response times have impeded the practical applicability of optical and thermal radiation detectors. In this investigation, we propose the utilization of superconducting Bi2Sr2CuOy (Bi-2201) as a pulsed laser-induced voltage material, revealing the emergence of notable transverse voltage signals in tilted thin films. A noteworthy peak voltage of 25.12 V is attained upon exposure to ultraviolet pulsed laser (248 nm), with a rapid rise time of merely 60 ns. Furthermore, we establish an empirical equation specific to our laser detection heterostructure, serving as a benchmark for Bi-2201-based laser detection systems. These findings introduce a promising avenue for the expanded practical applications of high-temperature superconductors. [ABSTRACT FROM AUTHOR]

We present FexOy composite particles prepared by pulsed laser irradiation of α-Fe2O3 nanoparticles dispersed in ethyl acetate and irradiated using a laser beam in the ultraviolet range with a wavelength of 355 nm. The sizes of particles and composition were controlled by tuning the laser parameters, such as laser fluence and irradiation time. We showed the evolution of the composition through X-ray diffraction measurements. Reactive bond molecular dynamics simulation results show bond breaking/formation during the synthesizing process. We examined the magnetic properties of the particles and showed that coercivity can be changed by the composition of particles and by increasing or decreasing particle size. The choice of systems built of iron and iron oxides made it possible to introduce the exchange bias effect into a range of magnetic properties of synthesized particles. [ABSTRACT FROM AUTHOR]

This study presents a two-step methodology, integrating support vector machine (SVM) and non-dominated sorting genetic algorithm II (NSGA-II) to model and optimize machining characteristics in laser-machined sapphire. In the first step, SVM was employed to predict the machined depth and surface roughness of sapphire substrates exposed to ultraviolet (UV) nanosecond laser pulses. A set of 27 systematic experiments, covering various levels of laser pulse energy, scanning speed, and hatching distance, was conducted to train SVM models. Both established SVM models showed remarkably low error values for the prediction of machined depth and surface roughness. An additional set of five experiments underscored the reliability of these SVM models. The laser machining outputs were extended by using the proposed SVM models to unveil the profound impact of processing parameters on machining characteristics. In the second step, the validated SVM models from the previous step were utilized as objective functions within the NSGA-II algorithm to maximize machined depth and minimize surface roughness simultaneously. This approach yielded a range of optimal solutions tailored to specific design requirements. It is found that by leveraging SVM in the first step to predict machined depth and surface roughness with exceptional accuracy, followed by the integration of NSGA-II for multi-objective optimization in the second step, the proposed approach offers a pioneering solution to unravel the intricate interplay of processing parameters and optimizing laser machining outcomes. These findings underscore the remarkable potential of the proposed two-step SVM–NSGA-II method in addressing a diverse array of engineering challenges. [ABSTRACT FROM AUTHOR]

As the global energy demand grows, maximizing oil extraction from known reserves has become critical. The study of microfluidic flow and transport in porous media has become a key direction for future subsurface energy technologies. However, the high requirements of fabrication techniques and materials have constrained the progress of micro-scale experiments. In this study, we have innovatively proposed a microfluidic chip fabrication method based on ultraviolet laser, and a set of visualized microdrive platforms is developed to allow direct observation of two-phase flow processes at the pore scale. In this study, two pore structures—one with low porosity and high connectivity and the other with high porosity but low connectivity—were constructed to investigate the effect of pore structure on recovery. Two micromodels with different pore structures were fabricated, and water and surfactant drive experiments were conducted at different drive rates, respectively. The results show that increasing the replacement rate and introducing surfactant can somewhat improve the final recovery. Using surfactant is more effective in enhancing the recovery rate than increasing the replacement rate. The complexity of pore structure is one of the main factors affecting the formation of residual oil. The microfluidic experimental setup proposed in this study reduces the time and cost of conventional practical methods. It permits visualization of the oil drive process, demonstrating that the Norland Optical Adhesive 81 (NOA81) micromodel is a valuable tool in two-phase flow studies and its applications. [ABSTRACT FROM AUTHOR]

Among all the nuclei, Thorium-229 has the lowest excited level at approximately 8.3 eV. This level is an isomeric state with a long radiative lifetime. Therefore, 229 Th can be excited to the isomeric state using a vacuum ultraviolet laser and is expected to have applications such as in frequency standards. Our group has been conducting experiments to excite 229 Th to the isomeric state via the second excited state using the high-intensity X-ray beam available at the SPring-8 facility. To detect vacuum ultraviolet photons from the isomeric state of 229 Th, a dedicated apparatus was constructed. We employed 229 Th-doped CaF 2 crystals as the irradiation target. Because these targets emit numerous scintillation photons due to nuclear decay and X-ray beam irradiation, detectors are required to significantly reduce these background events. To achieve this, we adopted dichroic mirrors and a photomultiplier tube for detecting scintillation photons by nuclear decay, in addition to a solar-blind photomultiplier tube for detecting decay photons from the isomeric state of 229 Th. In this proceedings paper, we describe the experimental apparatus used in the beamtime in 2023. [ABSTRACT FROM AUTHOR]

Laser induced damage sites on the surface of a KDP crystal component tend to grow with subsequent laser irradiation, which substantially decrease the lifetime of these optics. The structural investigation suggests that this may be related to the surface damage products of the crystals. In this work, the differences in the crystal structures, electronic properties and optical absorption between the KDP crystal and its surface laser-induced decomposition products K2H2P2O7 and KPO3 are investigated by using first-principles calculations. The theoretical results show that the nonlinear optical active units of KDP crystals are disrupted after irradiation dehydration to K2H2P2O7 and KPO3, which leads to the optical properties at the surface damage being deteriorated. In terms of the electronic structure, the dehydration products K2H2P2O7 and KPO3 have a shorter band gap compared with the KDP crystal. In addition, K2H2P2O7 and KPO3 have a wider optical absorption band than that of the KDP crystal and introduce more ultraviolet absorption in the optical elements. Compared to polycrystalline KDP at the bulk damage sites, the dehydration products at the surface damage increase the ultraviolet absorption of the crystals and cause the surface damage to continually grow under subsequent irradiation, whereas the bulk damage does not continue to increase in subsequent laser irradiation. [ABSTRACT FROM AUTHOR]

There is a widespread interest in time-resolved electron spectroscopies such as ultrafast electron diffraction, ultrafast electron microscopy, and ultrafast electron energy loss spectroscopy. These techniques require pulsed electron beams with both high current and brightness. LaB6 is commonly used as a thermionic emitter because of its low work function and high electron yield. However, its use as a pulsed photocathode has not been widely explored. Here, we present measurements of the electron yield from a LaB6 filament exposed to 392 nm UV ultrafast laser pulses under a wide range of filament temperatures. We find that sample heating strongly enhances photoelectron yield, an effect known as thermionically enhanced photoemission. However, it also creates potentially undesirable, continuous thermionic background. We conclude that the ideal optimal operating conditions strongly depend on the type of measurement and require defining and quantifying an appropriate figure of merit. [ABSTRACT FROM AUTHOR]

We present a detailed exposition of the design for time- and angle-resolved photoemission spectroscopy using a UV probe laser source that combines the nonlinear effects of β-BaB2O4 and KBe2BO3F2 optical crystals. The photon energy of the probe laser can be switched between 6.0 and 7.2 eV, with the flexibility to operate each photon energy setting under two distinct resolution configurations. Under the fully optimized energy resolution configuration, we achieve an energy resolution of 8.5 meV at 6.0 eV and 10 meV at 7.2 eV. Alternatively, switching to the other configuration enhances the temporal resolution, yielding a temporal resolution of 72 fs for 6.0 eV and 185 fs for 7.2 eV. We validated the performance and reliability of our system by applying it to measuring two typical materials: the topological insulator MnBi2Te4 and the excitonic insulator candidate Ta2NiSe5. [ABSTRACT FROM AUTHOR]

The effect of terahertz (THz) radiation has been studied in medicine. However, there is a lack of scientific information regarding its possible mutagenicity. Therefore, the present study aimed to assess the mutagenicity of 1.6 THz laser irradiation. The Ames test was conducted using five bacterial tester strains. The bacteria were subjected to (i) 1.6 THz laser irradiation at 3.8 mW/cm2 for 60 min using a tabletop THz pulse laser system, (ii) ultraviolet irradiation, (iii) treatment with positive control chemicals (positive control) or (iv) treatment with the solvent used in the positive control (negative control). After treatment, the bacterial suspensions were cultured on minimal glucose agar to determine the number of revertant colonies. In addition, the comet assay was performed using fibroblasts (V79) to assess possible DNA damage caused by the THz laser irradiation. The Ames test demonstrated that the THz laser irradiation did not increase the number of revertant colonies compared to that in the negative control group, whereas the ultraviolet irradiation and positive control treatment increased the number of revertant colonies. Thus, 1.6 THz laser irradiation is unlikely to be mutagenic. The comet assay additionally suggests that the THz laser irradiation unlikely induce cellular DNA damage. [ABSTRACT FROM AUTHOR]

We investigate the recrystallization of thick phosphorus-implanted GeSn layers using 308 nm Ultraviolet Nanosecond Laser Annealing (UV-NLA). We identify the optimal annealing conditions leading to the reconstruction of Ge0.92Sn0.08 crystal amorphized by dopant implantation. The fully recrystallized GeSn layers present specific structures with localized tin and strain variations. Above the non-amorphized and unmelted Ge0.92Sn0.08 seed layer, a first highly tensile strained GeSn sublayer is formed, with a tin gradient from 2.5% up to 10.5%. Closer to the surface, a second sublayer consists of tin-enriched vertical structures in a Ge0.93Sn0.07 matrix. Laser annealing enables us to reverse the strain of the GeSn layer. The initial GeSn presents a compressive strain of −0.10%, while the recrystallized Ge0.93Sn0.07 matrix is tensile strained at 0.39%. UV-NLA presents the advantages of (i) local annealing that recrystallizes amorphized GeSn layers after implantation without excessive tin segregation and (ii) reversing the strain of epitaxial GeSn layers from compressive to tensile. Our results open up promising perspectives for the integration of GeSn mid-IR photonic devices. [ABSTRACT FROM AUTHOR]

For the first time, a detailed comprehensive study is conducted of the dry etching of dislocation and dislocation-free samples of germanium on planes {111}, {110}, and {100}. Etching is performed by exposure to pulses of nanosecond ultraviolet (UV) laser radiation of the subthreshold intensity (wavelength, 355 nm; duration, ~10 ns; energy density, ~0.5–1.3 J/cm2; pulse repetition rate, 100 Hz; and divergence, 1–2 mrad). Before and after the laser heat treatment of the surface, the samples are examined using a Zygo optical profilometer and a scanning electron microscope. Features of the nature of the damage to the surfaces corresponding to different crystallographic planes of single crystals of industrial dislocation germanium are revealed. They are compared with the data on the subthreshold damage of typical dislocation-free crystals. It is shown that in dislocation samples of germanium on the {111} plane, it is possible to create a regime of exposure to radiation, leading to the formation of etch pits, which is outwardly identical to the dislocation pits detected during selective chemical etching. Their concentration corresponds in order of magnitude to the density of dislocations. On the {100} plane of dislocation samples, etching results are also found, which clearly have a crystallographic nature. At the energy density of the acting radiation ≥0.4 J/cm2 on the surfaces of dislocation (plane {100}) and dislocation-free germanium (planes {111}, {100}, {110}), only individual spots of ~50 µm and individual microcraters of ~0.1–1 µm having crystallographic features are recorded. The possibility of the environmentally friendly detection of dislocations in germanium without the use of chemical reagents is shown. [ABSTRACT FROM AUTHOR]

The prethreshold processes on the surface of copper and its alloys are investigated. In the absence of obvious traces of melting, while preserving the metal in a condensed state, under a nanosecond ultraviolet laser radiation energy density of 0.1–1.0 J/cm2, manifestations of high-temperature plastic deformation were observed. These are sliding and cracking along grain boundaries, within which crystallographic slipping was observed. A microprotrusion was formed on the surface of the irradiated zone, which was outwardly similar the distribution of laser radiation in the spot. The height of the microprotrusion reached 1 μm, and sometimes even more. An increase in the number of impacting impulses led to the accumulation of damage. The data obtained are in many ways similar to the acoustoplastic, electroplastic, and magnetoplastic effects. By analogy, we consider it possible to call the discovered effect optoplastic. [ABSTRACT FROM AUTHOR]

This work reports the microstructuring of cobalt (Co) thin films by high-energy UV pulsed laser irradiation. The parameters responsible for the efficient formation of such microstructures include laser fluence and film parameters. Cracks and island formations were observed for Co thin films deposited by RF sputtering. Such rough films rendered to produce inefficient microstructuring. To overcome this limitation, Co thin films were deposited by vacuum evaporation resulting in a smooth thin film compatible for laser-induced microstructuring. Two stages of conical patterning are discussed in terms of localized melting and abrupt condensation of the melted Co film owing to laser irradiation. An efficiency of 90% for laser-based microstructuring suggests that it is an efficient and non-invasive technique for fabricating nanostructures. [ABSTRACT FROM AUTHOR]

The present work provides an experimental investigation of a novel surface dielectric barrier discharge plasma actuator consisting of a 0.3 mm-thick alkali-free quartz substrate as dielectric barrier material and titanium-tungsten electrodes. The device is manufactured using ultraviolet lithography and CMOS processes, and experiments are conducted under sinusoidal plasma actuation in a vacuum chamber with pressure ranging from 20 kPa to 0.01 Pa. Intensified high-speed visualizations of the plasma discharge and electrical signals (current/voltage/power) define the diagnostic toolbox. Results highlight that at 20 kPa the plasma discharge is driven by the formation of micro sparks on the inner edge of the exposed electrode, propagating downstream in larger current structures. At 1 kPa, the plasma discharge becomes more glow-type with negative current regimes longer than the positive ones, while the voltage signals preserve their sinusoidal shape. In such a plasma regime, the discharge extends over the entire region covered by the electrodes, suggesting the use of larger grounded electrodes to further enlarge the actuation region. Furthermore, the momentum action of the plasma discharge is not anymore unidirectional as it acts on the whole device plane. At pressure between 50 Pa and 2.5 Pa, the plasma discharge is unstable exhibiting a fast modification of the plasma discharge. Below 2.5 Pa, it becomes a volumetric full glow-type, extending its action mainly upstream with a higher plasma density on the exposed electrode. The establishment of the new plasma regime at a pressure below 2.5 Pa affects the electrical dissipated power and asymmetry of voltage and current signals. • Novel plasma actuator using alkali-free quartz substrate and titanium-tungsten electrodes. • Plasma actuator characterization varying pressure from 20 kPa to 0.01 Pa. • Micro sparks are present at 20 kPa, glow-type discharge at 1 kPa, instability between 50 Pa and 2.5 Pa. • New regime below 2.5 Pa affects dissipated power and voltage–current asymmetry. [ABSTRACT FROM AUTHOR]

CsLiB6O10 (CLBO) is a high-performance nonlinear optical crystal, particularly suitable for high-power ultraviolet laser by fourth harmonic generation (FHG, 266 nm) and fifth harmonic generation (FIHG, 210 nm). A CLBO crystal with the size of 120 mm x 112 mm x 62 mm was successfully grown using top seeded solution growth (TSSG) method in this work. The grown CLBO crystal exhibits a complete appearance without macroscopic defects such as cracking and visible scattering particles. A CLBO FIHG crystal component was cut from this crystal, and its UV-visible-near infrared transmittance, optical uniformity and weak absorption properties were analyzed in detail. The results include that, the mean transmittance exceeds 90% from 210 nm to 1 800 nm, optical uniformity result is 3.8 x 10-5 and the weak absorption is 90 x 10-6cm-1 at 1 064 nm. All of these results indicate that the as-grown CLBO crystal possesses good transmittance in the ultraviolet region, high optical uniformity and low weak absorption, laying the foundation for subsequent research on related applications. [ABSTRACT FROM AUTHOR]

Development of novel ultraviolet (UV) upconversion materials has been emerging as a hot research topic for application in tunable UV lasers, photocatalysis, sterilization, tagging, and most recently luminescence thermometry. We readily synthesized a series of Ho3+/Gd3+ co-doped LiYO2 upconversion phosphors by a traditional high-temperature reaction. Under excitation from a blue ∼445 nm laser, LiYO2:Ho3+,Gd3+ polycrystalline powders yield intense sharp ultraviolet B (UVB) upconversion luminescence from Gd3+ 6Pj (j = 7/2, 5/2, 3/2) excited states. By means of steady and dynamic photoluminescence spectra, we systematically investigated the involved two-photon absorption upconversion as well as the accompanying energy transfer processes between Ho3+ and Gd3+ ions in the LiYO2 host lattice. Interestingly, the distinguishable UVB luminescence constituents from Gd3+ 6Pj excited states exhibit sensitive temperature dependence in a 353–673 K range. Shedding light on thermal equilibria between Gd3+ 6Pj UV-emitting levels, their luminescence intensity ratios follow Boltzmann statistics for the application of new luminescence thermometry. For the scheme of 6P7/2–6P3/2 thermally coupled levels, it works over a temperature range of 373–673 K with a maximum relative sensitivity (Sr) of about 1.07% K−1 at 373 K, and its 6P7/2–6P5/2 counterpart works over 353–533 K with a maximum Sr of about 0.83% K−1 at 353 K. Overall, our study provides a new pathway to develop UV upconversion materials, and promotes the application of Gd3+-related UV luminescence constituents in sensitive temperature sensing over a wide temperature range. [ABSTRACT FROM AUTHOR]

Our study presents laser-assisted methods to produce conductive graphene layers on the polymer surface. Specimens were treated using two different lasers at ambient and nitrogen atmospheres. A solid-state picosecond laser generating 355 nm, 532 nm, or 1064 nm wavelengths and a CO2 laser generating mid-infrared 10.6 µm wavelength radiation operating in a pulsed regime were used in experiments. Sheet resistance measurements and microscopic analysis of treated sample surfaces were made. The chemical structure of laser-treated surfaces was investigated using Raman spectroscopy, and it showed the formation of high-quality few-layer graphene structures on the PI surface. The intensity ratios I(2D)/I(G) and I(D)/I(G) of samples treated with 1064 nm wavelength in nitrogen atmosphere were 0.81 and 0.46, respectively. After laser treatment, a conductive laser-induced graphene layer with a sheet resistance as low as 5 Ω was formed. Further, copper layers with a thickness of 3–10 µm were deposited on laser-formed graphene using a galvanic plating. The techniques of forming a conductive graphene layer on a polymer surface have a great perspective in many fields, especially in advanced electronic applications to fabricate copper tracks on 3D materials. [ABSTRACT FROM AUTHOR]

The charge exchange (CE) reaction is an effective probe to study the structure of atomic nuclei in the isospin dimension, which has been studied for decades. To expand the range of nuclei studied by CE reactions to a wider range and research the structure characteristics of unstable nuclei, including the isospin symmetry, spin-isospin excitation, and nuclear symmetry energy, a semi-cylindrical time projection chamber (scTPC) prototype was designed and constructed to probe ( 3 He,t) CE reactions in inverse kinematics. The 266 nm UV laser was used to achieve electron-drift-velocity calibration. The scTPC has an energy resolution (FWHM) of 5.6% for α particles emitted by 241 Am radioactive source. The position resolution of scTPC is described by the residual method. The spatial resolution on the pad plane is 409 μ m. And the position resolution in the drift direction is 326 μ m, equivalent to an angular resolution of 0.4 ∘ . These performances suggest that the scTPC can measure Δ E and particle tracks precisely. The successful development of the scTPC prototype provides better conditions for the next step of experimental data analysis and processing. [ABSTRACT FROM AUTHOR]

In recent years, flexible sensors based on laser-induced graphene (LIG) have played an important role in areas such as smart healthcare, smart skin, and wearable devices. This paper presents the fabrication of flexible sensors based on LIG technology and their applications in human–computer interaction (HCI) systems. Firstly, LIG with a sheet resistance as low as 4.5 Ω per square was generated through direct laser interaction with commercial polyimide (PI) film. The flexible sensors were then fabricated through a one-step method using the as-prepared LIG. The applications of the flexible sensors were demonstrated by an HCI system, which was fabricated through the integration of the flexible sensors and a flexible glove. The as-prepared HCI system could detect the bending motions of different fingers and translate them into the movements of the mouse on the computer screen. At the end of the paper, a demonstration of the HCI system is presented in which words were typed on a computer screen through the bending motion of the fingers. The newly designed LIG-based flexible HCI system can be used by persons with limited mobility to control a virtual keyboard or mouse pointer, thus enhancing their accessibility and independence in the digital realm. [ABSTRACT FROM AUTHOR]

Preparing viable single cells is critical for conducting single‐cell RNA sequencing (scRNA‐seq) because the presence of ambient RNA from dead or damaged cells can interfere with data analysis. Here, we developed a method for isolating viable single cells from adult planarian bodies using fluorescence‐activated cell sorting (FACS). This method was then applied to both adult pluripotent stem cells (aPSCs) and differentiating/differentiated cells. Initially, we employed a violet instead of ultraviolet (UV) laser to excite Hoechst 33342 to reduce cellular damage. After optimization of cell staining conditions and FACS compensation, we generated FACS profiles similar to those created using a previous method that employed a UV laser. Despite successfully obtaining high‐quality RNA sequencing data for aPSCs, non‐aPSCs produced low‐quality RNA reads (i.e., <60% of cells possessing barcoding mRNAs). Subsequently, we identified an effective FACS gating condition that excluded low‐quality cells and tissue debris without staining. This non‐staining isolation strategy not only reduced post‐dissociation time but also enabled high‐quality scRNA‐seq results for all cell types (i.e., >80%). Taken together, these findings imply that the non‐staining FACS strategy may be beneficial for isolating viable cells not only from planarians but also from other organisms and tissues for scRNA‐seq studies. [ABSTRACT FROM AUTHOR]

The high acceptor ionization energy and, thus, low carrier concentration in p-type III-nitride have widely been recognized as the bottleneck preventing the development of high-efficiency light-emitting-diodes (LEDs). In this contribution, the influences of 193 nm pulsed laser annealing on the structure, electrical, and optical properties of p-type GaN were systematically analyzed. The hole concentration of p-GaN first increases and then decreases with increasing laser fluence, regardless of post-growth thermal annealing. The effective dopant activation due to laser annealing can be attributed to the dissociation of Mg–H complexes during the treatment. Laser-annealed p-GaN was utilized in a 280 nm deep ultraviolet LED. A maximum of 1.47 times higher wall-plug-efficiency enhancement factor was obtained compared to that without laser annealing, demonstrating that 193 nm laser annealing plays a decisive role in the boosting of quantum efficiency of optoelectronic devices. [ABSTRACT FROM AUTHOR]

The 'Astrocyte Network' and the understanding of its communication has been posed as a new grand challenge to be investigated by contemporary science. However, communication studies in astrocyte networks have investigated traditional petri-dish in vitro culture models where cells are closely packed and can deviate from the stellate form observed in the brain. Using novel cell patterning approaches, highly organised, regular grid networks of astrocytes on chip, to single-cell fidelity are constructed, permitting a stellate-like in vitro network model to be realised. By stimulating the central cell with a single UV nanosecond laser pulse, the initiation/propagation pathways of stellate-like networks are re-explored. The authors investigate the mechanisms of intercellular Ca2+ communication and discover that stellate-like networks of adult human astrocytes in vitro actually exploit extracellular ATP release as their dominant propagation pathway to cells in the network locally; being observed even down to the nearest neighbour and next nearest neighbouring cells—contrary to the reported gap junction. This discovery has significant ramifications to many neurological conditions such as epilepsy, stroke and aggressive astrocytomas where gap junctions can be targeted. In cases where such gap junction targeting has failed, this new finding suggests that these conditions should be re-visited and the ATP transmission pathway targeted instead. [ABSTRACT FROM AUTHOR]