Light Pulses Research Articles

An optogenetic method for the controlled release of single molecules

We developed a system for optogenetic release of single molecules in cells. We confined soluble and transmembrane proteins to the Golgi apparatus via a photocleavable protein and released them by short pulses of light. Our method allows for a light dose-dependent delivery of functional proteins to the cytosol and plasma membrane in amounts compatible with single-molecule imaging, greatly simplifying access to single-molecule microscopy of any protein in live cells. We were able to reconstitute ion conductance by delivering BK and LRRC8/volume-regulated anion channels to the plasma membrane. Finally we were able to induce NF-kB signaling in T lymphoblasts stimulated by interleukin-1 by controlled release of a signaling protein that had been knocked out. We observed light-induced formation of functional inflammatory signaling complexes that triggered phosphorylation of the inhibitor of nuclear factor kappa-B kinase only in activated cells. We thus developed an optogenetic method for the reconstitution and investigation of cellular function at the single-molecule level.

Efficacy and safety of the combination of oral tranexamic acid and intense pulsed light versus oral tranexamic acid alone in the treatment of refractory Riehl's melanosis: A prospective, comparative study.

There is no standardized and effective treatment modality for Riehl's melanosis. To compare the efficacy and safety of oral tranexamic acid (TXA) combined with intense pulsed light (IPL) versus TXA alone in the treatment of refractory Riehl's melanosis. A prospective study of 28 subjects with refractory Riehl's melanosis and Fitzpatrick Skin Types III or IV was conducted. All subjects received oral TXA 500 mg daily and 11 of them were treated in combination with monthly IPL therapy for 6 months. The primary outcome measure was mean melanin index (MI), erythema index (EI) and acquired dermal macular hyperpigmentation area and severity index (DPASI). The Physician Global Assessment (PGA) and patient satisfaction scale were documented. After treatment, DPASI, mean MI, and EI were significantly reduced in both groups. The group treated with combination therapy showed better improvement according to MI (p = 0.0032) and DPASI (p = 0.00468). PGA and patient satisfaction scale showed superior efficacy in the combination group. No significant difference was observed in treatment-related side effects. The combination of oral TXA and IPL proves to be a safe and satisfactory treatment strategy for refractory Riehl's melanosis.

Pattern effect suppression of pulse signals based on pre-signal control method

By using the pre-signal light as the control light, we propose a method to suppress the transient effect of erbium-doped fiber amplifiers for low-frequency pulse signals. The pattern effect of the pulse signals within the low frequency range (400–1000 Hz) and 1550 nm band is relieved, and the optical surge coefficient Cs decreases to about 0.54 dB. Experimental results show that the proposed method has better performances in suppressing pattern effect in comparison with the conventional continuous light control scheme and higher output gain compared to the compensation pulsed light method. Our proposed pattern effect suppression approach based on the pre-signal control method is anticipated to find promising applications in the field of optical communications.

Orbitronics: light-induced orbital currents in Ni studied by terahertz emission experiments

Orbitronics is based on the use of orbital currents as information carriers. Orbital currents can be generated from the conversion of charge or spin currents, and inversely, they could be converted back to charge or spin currents. Here we demonstrate that orbital currents can also be generated by femtosecond light pulses on Ni. In multilayers associating Ni with oxides and nonmagnetic metals such as Cu, we detect the orbital currents by their conversion into charge currents and the resulting terahertz emission. We show that the orbital currents extraordinarily predominate the light-induced spin currents in Ni-based systems, whereas only spin currents can be detected with CoFeB-based systems. In addition, the analysis of the time delays of the terahertz pulses leads to relevant information on the velocity and propagation length of orbital carriers. Our finding of light-induced orbital currents and our observation of their conversion into charge currents opens new avenues in orbitronics, including the development of orbitronic terahertz devices.

The breakup and instability structures of liquid jets in subsonic crossflows

The breakup of water and Jet A fuel jets injected transverse into elevated temperature (up to 425 °C), combustion pre-heated, subsonic crossflows was investigated by internally fluorescing the liquid jet column. The fluorescent dye seeded test liquids were illuminated by a pulsed laser light that was transmitted within the injector using a quartz rod light-guide. High-resolution images isolating the intact liquid column from light scattered by the surrounding dense spray facilitated precise measurement of the liquid column breakup position and the size and distribution of windward column instability waves. The injector geometry consisted of a 1 mm circular orifice with an orifice length of 20 mm with a tapered inlet. Liquid jet to gaseous crossflow momentum flux ratios were varied from 6 to 266 and the gas Weber number was varied from 10.7 to 228. Empirical correlations were derived for the liquid column breakup coordinates and breakup time in addition to the average and local maximum instability wavelength and amplitude on the liquid column windward surface. The reported correlations provided key insight into atomization physics and aim to support the quantitative validation of high-fidelity numerical simulations of the liquid jet in subsonic crossflow.

Correcting the Non-Linear Response of Silicon Photomultipliers.

The finite number of pixels in a silicon photomultiplier (SiPM) limits its dynamic range to light pulses up to typically 80% of the total number of pixels in a device. Correcting the non-linear response is essential to extend the SiPM's dynamic range. One challenge in determining the non-linear response correction is providing a reference linear light source. Instead, the single-step method used to calibrate PMTs is applied, based on the difference in responses to two light sources. With this method, the response of an HPK SiPM (S14160-1315PS) is corrected to linearity within 5% while extending the linear dynamic range by a factor larger than ten. The study shows that the response function does not vary by more than 5% for a variation in the operating voltage between 2 and 5 V overvoltage in the gate length between 20 and 100 ns and for a time delay between the primary and secondary light of up to 40 ns.

Competition of multiphoton ionization pathways in lithium

We study the three-photon ionization of atomic lithium by intense, short light pulses, via numerically solving the time-dependent Schrödinger equation. Two-photon Rabi oscillations are induced between the 2s and 4s states, which are damped due to single-photon ionization to the p continuum. Developing a minimal three-level model, we analyze the spectral features of the Autler–Townes (AT) doublet that is formed upon the resonant coupling with the laser pulse. Furthermore, we show that this 2s→→4s→p continuum pathway is the dominant process, if the duration of the laser pulse exceeds a certain value. For shorter pulses, ionization through the 2p state ( 2s→2p→4d→f continuum ) gradually becomes the dominant process, provided that the pulse is strong enough to induce several Rabi floppings. Here, we trace the competition of these ionization pathways by observing the structural changes in the shape of the AT doublet.

Pulsed light processing of low sugar, added fiber RTD mango beverage

AbstractReady‐to‐drink (RTD) mango beverage enriched with short‐chain fructooligosaccharides (scFOS) was developed to reduce added sugar and incorporate a soluble prebiotic fiber. The impact of pulsed light (PL) technology on microbial inactivation, enzyme activity, and quality attributes in scFOS‐enriched mango RTD beverages was investigated. Effective PL fluence of 0.12–1.2 J/cm2 was employed on mango beverage in order to maximize the retention of nutritional properties along with inactivation of microbial and enzymatic activity. There is complete inactivation of microbial load and enzymatic activity with 72.45, 84.17, 88, 78.79, and 77.63% retention of ascorbic acid, antioxidants, total phenolics, total flavonoids, and total carotenoids in 6% scFOS mango beverage at an effective fluence of 1.2 J/cm2. There is no wide change in TSS, pH, and TA in all the PL treatments. The scFOS increased viscosity, and it also protected bioactives, namely, carotenoids, ascorbic acid, and phenolics, from photoxidation caused by PL. Results showed that scFOS allowed a substantial reduction in added sugar and increased soluble fiber content in the beverage. Sensory score of 3 and 6% scFOS‐enriched beverages were closely comparable with control. The study showcases the potential of scFOS to enhance the nutritional profile of beverages. It also highlights the effectiveness of PL processing in pasteurization fruit beverages, meeting stakeholders' demands for microbial safety, enzymatic stability, and nutrient retention.Practical applicationsThe practical applications of this research hold significant promise for the food and beverage industry. The innovative formulations of ready‐to‐drink (RTD) mango beverages not only reduce added sugar by up to 52% but also increase fiber content from 0.6 to 6%, meeting consumer demands for healthier options. The integration of pulsed light technology effectively targets microbial and enzyme inactivation, complying with Food and Drug Administration standards and offering a viable processing method. The incorporation of short‐chain fructooligosaccharides enhances the protection of bioactive compounds during pulsed light treatment, ensuring higher retention of antioxidants, vitamins, and other valuable components. This advancement contributes to improved nutritional profiles while maintaining sensory appeal. These findings have the potential to revolutionize RTD beverage production, addressing health‐conscious consumer preferences, and enhancing product quality.

High-Fluence Epithelium-off Accelerated Pulsed Corneal Cross-linking (15 mW/cm2; 7.2 J/cm2) for Pediatric Keratoconus: A 3-Year Retrospective Analysis.

To assess the safety and efficacy of treatment and secondarily determine the topographic changes, visual outcomes, and demarcation line depth after high-fluence pulsed light accelerated cross-linking (ACXL) in pediatric patients (younger than 18 years) with progressive keratoconus. This retrospective analysis included 32 eyes (25 children, aged 11 to 18 years), with progressive keratoconus treated with high-energy epithelium-off pulsed light ACXL (7.2 J/cm2, 15 mW/cm2, 12 minutes, 2 seconds on/1 second off). Corrected distance visual acuity (CDVA), Scheimpflug tomography, and anterior optical coherence tomography measurements were recorded preoperatively and 1, 2, and 3 years postoperatively. A total of 32 eyes were included. Significant CDVA improvement, pachymetry, and maximum keratometry reduction were found at all follow-up visits. Mean keratometric values remained stable, and astigmatism showed a mild worsening (< 0.25 D) with statistical significance at 1 and 3 years. Total aberration showed discordant results and coma aberration had a slight improvement without statistical significance. The demarcation line depth was 265 ± 26 μm. Three patients developed mild haze without visual acuity loss. None of the patients underwent a second CXL procedure. In pediatric patients, high-fluence epithelium-off pulsed light ACXL appears to be a safe and effective procedure to halt the progression of keratoconus, slightly improving the CDVA and keratometric values. [J Refract Surg. 2024;40(3):e148-e155.].

TIPS-pentacene organic field-effect transistor for optoelectronic neuromorphic simulation

Biological learning and memory of visual information are carried out through the regulation of synaptic weight by visual neuron synapses. Replicating the cognitive processes and light-induced adaptability of the human brain holds immense significance for the advancement of artificial intelligence. Here, we propose an organic photoelectric synaptic transistor based on 6,13-bis(triisopropylsilylethynyl) pentacene. The device showcases a memory window greater than 20 V and current on/off ratio of 106. Synaptic behavior transition is exhibited from short-term plasticity to long-term plasticity under photoelectric pulse modulation, including paired-pulse facilitation, spike time dependent plasticity, spike number dependent plasticity and optical enhancement/electrical inhibition. In addition, we simulate the learning and adaptation process of the synaptic device after long-term light stimulation, and recognize visual information by perceiving light pulses in different time domains.

Assessment of P700 Redox State of Tomato Plants Under the Combined Influence of Elevated Temperature and Fusarium oxysporum Infection by Differential Absorption Photometry Using Saturating Light Pulse Technology

Assessment of P700 Redox State of Tomato Plants Under the Combined Influence of Elevated Temperature and Fusarium oxysporum Infection by Differential Absorption Photometry Using Saturating Light Pulse Technology

Dynamics of microcavities created by nonharmonic unipolar light pulses in a resonant medium

Dynamics of microcavities created by nonharmonic unipolar light pulses in a resonant medium

Nonthermal Sterilization of Animal-based Foods by Intense Pulsed Light Treatment.

The consumption of meat has been increasing, leading to a dynamic meat and meat processing industry. To maintain the quality and safety of meat products, various technologies have been explored, including intense pulsed light (IPL) technology. Several factors affect the inactivation of microorganisms by IPL treatment, including light intensity (fluence), treatment duration, pulse frequency, and the distance between the lamp and the samples. Meat products have been studied for IPL treatment, resulting in microbial reductions of approximately 0.4-2.4 Log. There are also impacts on color, sensory attributes, and physico-chemical quality, depending on treatment conditions. Processed meat products like sausages and ham have shown microbial reductions of around 0.1-4 Log with IPL treatment. IPL treatment has minimal impact on color and lipid oxidation in these products. Egg products and dairy items can also benefit from IPL treatment, achieving microbial reductions of around 1-7.8 Log. The effect on product quality varies depending on the treatment conditions. IPL technology has shown promise in enhancing the safety and quality of various food products, including meat, processed meat, egg products, and dairy items. However, the research results on animal-based food are not diverse and fragmentary, this study discusses the future research direction and industrial application through a review of these researches.

Pattern-dependent resistivity variations in inkjet-printed conductors due to non-uniform ink drying

When fabricating inkjet-printed electronic devices and circuits, inkjet-printed conductive materials require drying and sintering to improve electrical conductivity. Electrical conductivity should be the same irrespective of pattern design, size, location, or density of adjacent patterns. However, we demonstrate that spatial variations in the drying process for inkjet-printed patterns with proximity to others cause resistivity variations. These resistivity variations are studied here experimentally for different circuit patterns and in arrays of inkjet-printed square electrodes. This variation depends not only on the location of each electrode in an array but also on the number of electrodes. This means that for the same drying temperature and duration, the array with a larger number of electrodes exhibits a larger resistivity variation. The sooner an electrode dries, the lower resistivity it achieves. The resistivity variation between an individual electrode and the center electrode in a 7 × 7 electrode array can be a factor of seven. This variation decreases for lower numbers of electrodes to a factor of three for a 3 × 3 array. Furthermore, x-ray photoelectron spectroscopy analyses provide evidence for the residual presence of carbon-based materials within electrodes after the drying process. These results confirm that the location of electrodes within an array significantly influences the amount of residual carbon-based materials, thereby contributing to resistivity variations. Although intense pulsed light sintering can decrease this variation, its optimal parameters depend on the printed designs, and our simulation results show a non-uniform temperature profile over the electrode arrays. Temperature increases more at the center of patterns than the corners, which can be useful in this case to improve resistivity uniformity. In this study, for the first time, we show how different printed shapes and designs can result in non-uniform resistivity after drying and sintering.

Transient positron annihilation spectroscopy under light irradiation at liquid nitrogen temperature: evaluation of defect states in single-crystal ZnO

Abstract A time-dependent measurement system has been developed for positron annihilation spectroscopy to study the effects of light irradiation at liquid nitrogen temperature. The system enables the measurement of positron annihilation lifetimes after pulse light irradiation, utilizing various time windows to investigate the transient changes of photo-excited vacancy-type defects. Additionally, this system facilitates coincidence Doppler broadening measurements during light irradiation at liquid nitrogen temperature. The system was successfully employed to analyze changes in positron lifetime and positron annihilation sites in electron-irradiated single-crystalline ZnO under light irradiation.

Результаты исследования эффективности комплексной терапии, включающей топические средства Liftactiv B3 и IPL-терапию, в лечении пациентов с мелазмой

Purpose of the study. Comparative assessment of the effectiveness of the combined protocol of IPL therapy, serum and Liftactiv B3 cream in patients with hyperpigmentation (melasma) in accordance with clinical and special research methods. Material and methods. The study included 60 patients in 2 groups. Patients in the main group and the control group received IPL therapy procedures once every 4 weeks, 3 procedures per course. In the main group, all patients used a daily alternation of serum and Liftactiv B3 cream. In the control group, patients used photoprotective cream SPF 30. Special methods included: digital dermatoscopy, mexametry. Clinical methods included: mMASI index, MELASQoL quality of life scale, GAIS scale. Results. According to the dynamics of the mMASI index at control point V5: the decrease in the main group was 87.9%, in the control group – 60.0%. The decrease in mexametry compared to the control point V1 in the main group in V5 was 90.1%, in the control group –60.1%. The decrease in the MELASQoL index at point V5 in the main group was 90.3%, in the control group – 59.9%. According to GAIS (patient), in the control group, 26.7% of patients achieved significant improvement, 73.3% –moderate improvement, in the main group, 60% of patients achieved significant improvement, 40% – moderate improvement. According to GAIS (researcher), in the control group, 33.3% of patients achieved significant improvement, 66.7% – moderate improvement, in the main group, 70% of patients achieved significant improvement, 30% – moderate improvement. Conclusions. The combined use of IPL therapy (3 procedures), serum and Liftactiv B3 cream is more effective than monotherapy with broadband pulsed light during a 12-week follow-up period. The obtained results about the lower effectiveness of IPL therapy compared to the complex method can be explained by the synergistic effect of the combination of a physiotherapeutic factor and an external drug, the wide spectrum of action of Liftactiv B3 topical agents (influence on various pathogenetic mechanisms of melasma), as well as the need to carry out a larger number of procedures for mono broadband light therapy.

Chirped self-similar optical solitons with cubic–quintic–septic–nonic form of self-phase modulation

This study investigates the dynamics of ultrashort light pulses in an inhomogeneous optical medium exhibiting all orders of nonlinearity up to the ninth order. The research focuses on exploring the existence and properties of self-similar solitons while varying cubic, quintic, septic, and nonic nonlinearities, group velocity dispersion, and loss or gain. It is found that the transmission system supports the existence of novel types of self-similar bright and dark pulses in the presence of various physical processes. Importantly, these self-similar localized waves exhibit a linear chirp, a crucial factor for achieving effective pulse amplification or compression. Based on the chirp property, the dynamical behaviors of these self-similar waveforms are discussed in a periodically distributed amplification system. The findings highlight that the shape and dynamics of these chirped self-similar pulses can be precisely controlled by selecting appropriate profiles for gain or loss, nonlinearity, and dispersion. Additionally, the research numerically discusses the interaction dynamics between two and three adjacent solitons.

Light-induced switching between singlet and triplet superconducting states

While the search for topological triplet-pairing superconductivity has remained a challenge, recent developments in optically stabilizing metastable superconducting states suggest a new route to realizing this elusive phase. Here, we devise a testable theory of competing superconducting orders that permits ultrafast switching to an opposite-parity superconducting phase in centrosymmetric crystals with strong spin-orbit coupling. Using both microscopic and phenomenological models, we show that dynamical inversion symmetry breaking with a tailored light pulse can induce odd-parity (spin triplet) order parameter oscillations in a conventional even-parity (spin singlet) superconductor, which when driven strongly can send the system to a competing minimum in its free energy landscape. Our results provide new guiding principles for engineering unconventional electronic phases using light, suggesting a fundamentally non-equilibrium route toward realizing topological superconductivity.

Contribution of the eye and of opn4xa function to circadian photoentrainment in the diurnal zebrafish.

The eye is instrumental for controlling circadian rhythms in mice and human. Here, we address the conservation of this function in the zebrafish, a diurnal vertebrate. Using lakritz (lak) mutant larvae, which lack retinal ganglion cells (RGCs), we show that while a functional eye contributes to masking, it is largely dispensable for the establishment of circadian rhythms of locomotor activity. Furthermore, the eye is dispensable for the induction of a phase delay following a pulse of white light at CT 16 but contributes to the induction of a phase advance upon a pulse of white light at CT21. Melanopsin photopigments are important mediators of photoentrainment, as shown in nocturnal mammals. One of the zebrafish melanopsin genes, opn4xa, is expressed in RGCs but also in photosensitive projection neurons in the pineal gland. Pineal opn4xa+ projection neurons function in a LIGHT ON manner in contrast to other projection neurons which function in a LIGHT OFF mode. We generated an opn4xa mutant in which the pineal LIGHT ON response is impaired. This mutation has no effect on masking and circadian rhythms of locomotor activity, or for the induction of phase shifts, but slightly modifies period length when larvae are subjected to constant light. Finally, analysis of opn4xa;lak double mutant larvae did not reveal redundancy between the function of the eye and opn4xa in the pineal for the control of phase shifts after light pulses. Our results support the idea that the eye is not the sole mediator of light influences on circadian rhythms of locomotor activity and highlight differences in the circadian system and photoentrainment of behaviour between different animal models.

Toluene alters the intrinsic excitability and excitatory synaptic transmission of basolateral amygdala neurons.

Inhalant abuse is an important health issue especially among children and adolescents who often encounter these agents in the home. Research into the neurobiological targets of inhalants has lagged behind that of other drugs such as alcohol and psychostimulants. However, studies from our lab and others have begun to reveal how inhalants such as the organic solvent toluene affect neurons in key addiction related areas of the brain including the ventral tegmental area, nucleus accumbens and medial prefrontal cortex. In the present study, we extend these findings and examine the effect of toluene on electrophysiological responses of pyramidal neurons in the basolateral amygdala BLA, a region important for generating emotional and reward based information needed to guide future behavior. Whole-cell patch-clamp electrophysiology recordings of BLA pyramidal neurons in rat brain slices were used to assess toluene effects on intrinsic excitability and excitatory glutamatergic synaptic transmission. Acute application of 3 mM but not 0.3 mM toluene produced a small but significant (~20%) increase in current-evoked action potential (AP) firing that reversed following washout of the toluene containing solution. The change in firing during exposure to 3 mM toluene was accompanied by selective changes in AP parameters including reduced latency to first spike, increased AP rise time and decay and a reduction in the fast after-hyperpolization. To examine whether toluene also affects excitatory synaptic signaling, we expressed channelrhodopsin-2 in medial prefrontal cortex neurons and elicited synaptic currents in BLA neurons via light pulses. Toluene (3 mM) reduced light-evoked AMPA-mediated synaptic currents while a lower concentration (0.3 mM) had no effect. The toluene-induced reduction in AMPA-mediated BLA synaptic currents was prevented by the cannabinoid receptor-1 antagonist AM281. These findings are the first to demonstrate effects of acute toluene on BLA pyramidal neurons and add to existing findings showing that abused inhalants such as toluene have significant effects on neurons in brain regions involved in natural and drug induced reward.