Static in-situ curing characteristics of CFRP based on near infrared laser.

STUDY ON STATIC IN-SITU CURING CHARACTERISTICS OF CFRP BASED ON NEAR INFRARED LASER: The quick curing method of carbon fibre reinforced plastics (CFRP) is one of the hotspots in current research. A static in-situ curing method for CFRP prepreg based on near-infrared laser was put forward in this study. The in-situ curing structural characteristics and the mechanism of CFRP were investigated through real-time surface temperature measurement, COMSOL temperature field simulation, 3D measurement of curing morphology and resin curing degree test. The thermal conductivity of the CFRP along the fiber direction is considerably higher than that along the perpendicular fiber direction. As a result, the temperature profile in the plane takes on an elliptical shape. During the transfer, the temperature field gradually decreases, resulting in an ellipsoidal 3D high-temperature distribution. The different shrinkage phenomena in the different curing regions between the layers lead to an irregular ellipsoidal solidification morphology of the unidirectional CFRP. The temperature in the center of the heat affected zone increases as a power exponential function with time. The area and depth of the heat-affected zone increases with the laser power, and the curing area is positively correlated with the degree of curing. As a result, curing temperature governing equations based on laser power and layer thickness have been proposed, while relationship equations based on laser power, curing depth and curing morphology have been developed. In addition, prediction equations based on curing morphology have been developed for curing degree, in order to achieve precise curing of CFRP.

NIR Laser Irradiation Promotes Osteogenic Differentiation of PDLSCs Through the Activation of TRPV1 Channels and Subsequent Calcium Signaling.

Near-infrared (NIR) irradiation has shown potential to stimulate osteogenic differentiation, but the mechanisms are not fully understood. The study is to investigate the effects of NIR laser irradiation on osteoblastic differentiation. Human periodontal ligament stem cells (hPDLSCs) were cultured in osteogenic medium and exposed to 810 nm NIR laser at 0.5 J/cm2 every 48 h. The transient receptor potential vanilloid (TRPV1) channel inhibitor capsazepine (CPZ) was used to evaluate the role of calcium influx. Osteogenic differentiation was assessed by proliferation (CCK-8), alkaline phosphatase (ALP) activity, mineralization (Alizarin Red), and expression of bone markers by PCR and Western blot over 2 weeks. Intracellular calcium was measured by Fluo-4M dye and flow cytometry. Results showed that NIR irradiation enhanced hPDLSC proliferation, ALP activity, mineralization, and bone marker expression, indicating increased osteogenic differentiation. These effects were inhibited by CPZ. NIR induced a transient rise in intracellular calcium peaking at 3 min, which was blocked by CPZ. In conclusion, this study demonstrates that NIR laser irradiation promotes osteogenic differentiation of PDLSCs through the activation of TRPV1 channels and subsequent calcium signaling. Further research is warranted to optimize the treatment parameters and elucidate the detailed signaling pathways involved, paving the way for the clinical application of NIR therapy in the treatment of bone disorders and periodontal disease.

Near-infrared laser diode mitigates Aß1-42-induced neurodegeneration in cortical neurons.

Alzheimer's disease, a prevalent neurodegenerative condition primarily affecting older adults, remains incurable. Its principle pathological hallmark is the accelerated accumulation of amyloid ß (Aß) protein. This study investigates the potential of photobiomodulation using near infrared light to counteract Aß1-42-induced synaptic degeneration and neurotoxicity. We focused on the effect of 808 nm near-infrared laser diode (LD) on Aß1-42 cytotoxicity in primary cultured cortical neurons. We assessed cell survival using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, observing substantial benefits from LD irradiation with a power of 10 mW and a dose of 30 J. Cells exposed to Aß1-42 exhibited morphological changes indicative of synaptic damage and a significant decrease in the number of postsynaptic density protein-95 (PSD-95) contacts, which were significantly improved with near-infrared LD therapy. Furthermore, this therapy reduced Aß and phosphorylated tau (P-tau) protein accumulation. Additionally, near-infrared LD irradiation substantially lessened the Aß1-42-induced rise in glial fibrillary acid protein (GFAP) and ionized calcium-binding adaptor molecule 1 (IBA1) in astrocytes and microglia. Remarkably, near-infrared LD irradiation effectively inhibited phosphorylation of key proteins involved in Aß1-42-induced necroptosis, namely Receptor-interacting protein kinase-3 (RIP3) and Mixed Lineage Kinase domain-Like protein (MLKL). Our findings suggest that near-infrared LD treatment significantly reduces neurodegeneration by reducing glial overactivation and neuronal necroptosis triggered by Aß1-42. Thus, near-infrared LD treatment emerges as a promising approach for slowing or treating Alzheimer's disease, offering new avenues in its management.

Photobiomodulation with near-infrared laser for tinnitus management: preliminary animal experiments and randomized clinical trials.

This study investigates the effectiveness of photobiomodulation therapy (PBMT) in treating chronic high-frequency tinnitus with the TINI device, a near-infrared (830 nm) laser. The study includes preliminary animal experiments with 28 mice and a randomized controlled trial with 56 participants to examine the functional and molecular changes in the auditory system that PBMT may cause. The animal model used sodium salicylate to induce tinnitus, followed by PBMT, which showed promising reductions in the behavioral evidence of tinnitus and a reversal of tinnitus-associated upregulation of vesicular glutamate transporters 2 expression in the ipsilateral dorsal cochlear nucleus (p < 0.05). In the clinical trial, participants with chronic high-frequency tinnitus received trans-tympanic application of the TINI device. The results did not show a significant difference in tinnitus score at the final time point when compared to the sham group. However, questionnaires revealed significant improvements in tinnitus symptoms and psychological outcomes following treatment with the TINI device compared to before treatment (p < 0.05). These findings suggest that while PBMT has potential benefits, its clinical effectiveness may be unclear due to its complex nature and interaction with other conditions. Further research is required to optimize treatment parameters and gain a complete understanding of the therapeutic potential of PBMT in managing tinnitus.

Nanosecond infrared laser (NIRL) for cutting roots of human teeth: thermal effects and quality of cutting edges.

A nanosecond infrared laser (NIRL) was investigated in cutting dental roots. The focus of the investigation was defining the preparation accuracy and registration of thermal effects during laser application. Ten teeth were processed in the root area using a NIRL in several horizontal, parallel incisions to achieve tooth root ablation as in an apicoectomy. Temperature change was monitored during ablation and the quality of the cutting edges in the roots were studied by means of micro-CT, optical coherence tomography, and histology of decalcified and undecalcified specimens. NIRL produced clearly defined cut surfaces in dental hard tissues. The automated guidance of the laser beam created regular, narrow dentin defects that tapered in a V-shape towards the ablation plane. A biologically significant increase in the temperature of the object and its surroundings did not occur during the laser application. Thermal dentin damage was not detected in histological preparations of treated teeth. Defined areas of the tooth root may be ablated using a NIRL. For clinical translation of NIRL in apicoectomy, it would be necessary to increase energy delivered to hard tissue and develop beam application facilitating beam steering for oral treatment.

NIR-II Light-Actuated Nanomotors for Enhanced Photoimmunotherapy Toward Hepatocellular Carcinoma.

Light-propelled nanomotors, which can convert external light into mechanical motion, have shown considerable potential in the construction of a new generation of drug delivery systems. However, the therapeutic efficacy of light-driven nanomotors is always unsatisfactory due to the limited penetration depth of near-infrared-I (NIR-I) light and the inherent biocompatibility of the motor itself. Herein, an asymmetric nanomotor (Pd@ZIF-8/R848@M JNMs) with efficient motion capability is successfully constructed for enhanced photoimmunotherapy toward hepatocellular carcinoma. Under near-infrared-II (NIR-II) irradiation, Pd@ZIF-8/R848@M JNMs convert light energy into heat energy, exhibiting self-thermophoretic locomotion to penetrate deeper into tumor tissues to achieve photothermal therapy. At the same time, functionalized with an immune-activated agent Resiquimod (R848), our nanomotors could convert a "cold tumor" into a "hot tumor", transforming the immunosuppressive microenvironment into an immune-activated state, thus achieving immunotherapy. Dual photoimmunotherapy of the as-developed NIR-II light-driven Pd@ZIF-8/R848@M JNMs demonstrates considerable tumor inhibition effects, offering a promising therapeutic approach in the field of anticancer therapy.

Sm3+ as effective deactivator for enhanced ∼3 µm laser emission in Er,Sm:SrLaAlO4 crystal.

A promising mid-infrared (MIR) laser crystal with Er, Sm co-doped SrLaAlO4 (Er,Sm:SLA) crystal was successfully grown using the Czochralski (CZ) method. It was the first time that co-doped Sm3+ ion as deactivator for Er3+ activated âˆ¼ 3.0 µm laser. The crystal structure, absorption spectra, emission spectra, and energy level lifetime were discussed in detail. The band structure and density of states were calculated by the density functional theory. The spectral parameters were calculated using Judd-Ofelt (J-O) theory and the deactivate effect of Sm3+ was systematically studied. The introduction of Sm3+ ions enhance the 2.7 µm mid infrared emission intensity by three times, and decrease the lifetime of 4I13/2 energy level of Er3+ ion from 4.35 ms to 0.98 ms. The lifetime ratio of upper and lower levels for 2.7 µm emission was calculated to be 0.63, which is 2.6 times of Er:SLA crystal and comparable to some commercial crystals. All the results indicate that the Sm3+ ion is an effective deactivator for âˆ¼3 µm laser emission. The long upper level lifetime, as well as the large lifetime ratio, the broadening spectra characteristics and the appropriate emission cross-section show the Er,Sm:SLA crystal a good gain material for ultrafast and tunable lasers at âˆ¼3.0 µm.

Simultaneous sealing and bisection of porcine renal blood vessels, ex vivo, using a continuous-wave, infrared diode laser at 1470 nm.

Electrosurgical and ultrasonic devices are used in surgical procedures for hemostatic sealing and bisection of vascular tissues. Previous benchtop studies alternatively demonstrated successful infrared laser sealing and cutting of blood vessels, in a sequential, two-step approach. This study describes a smaller, laparoscopic device compatible design, and simultaneous approach to sealing and bisection of vessels, with potential optical feedback. A 1470-nm infrared diode laser sealed and bisected 40 porcine renal arteries, ex vivo. A reciprocating, side-firing, optical fiber, housed in a transparent square quartz optical chamber (2.7 × 2.7 × 25 mm outer dimensions), delivered laser energy over an 11 mm scan length, with a range of incident powers (41-59 W) and treatment times (5-21 s). Vessel diameters ranged from 2.5 to 4.8 mm. Vessel burst pressure measurements were performed on each cut end (n = 80) with success indicated by pressures exceeding 360 mmHg. All vessel ends were successfully sealed and bisected (80/80). The highest incident power, 59 W, yielded short treatment times of 5-6 s. Peak temperatures on the external chamber surface reached 103 oC. Time to cool down to body temperature measured 37 s. Infrared lasers simultaneously seal and bisect blood vessels, with treatment times comparable to, and temperatures and cooling times lower than reported for conventional devices. Future work will focus on integrating the fiber and chamber into a standard 5-mm-outer-diameter laparoscopic device. Customization of fiber scan length to match vessel size may also reduce laser energy deposition, enabling lower peak temperatures, treatment times, and cooling times.

Electrospun medicated gelatin/polycaprolactone Janus fibers for photothermal-chem combined therapy of liver cancer.

Liver cancer is a common cancer in the world, and core-shell nanoparticles as a commonly used combination therapy for local tumor ablation, have many shortcomings. In this study, photothermal Janus nanofibers were prepared using a electrospinning technology for tumor treatment, and the products were characterized and in vitro photothermal performance investigated. The micromorphology analysis showed that the photothermic agent CuS and electrospun fibers (loaded with CuS and anticancer drug dihydromyricetin) were successfully prepared, with diameters of 11.58 ± 0.27 µm and 1.19 ± 0.01 µm, respectively. Water contact angle and tensile test indicated that the fiber membranes has a certain hydrophilic adhesion and excellent mechanical strength. The fiber membranes has 808 nm near-infrared laser photothermal heating performance and photothermal stability, and it also has a strong response to the laser that penetrates biological tissue. In addition, in vitro cell culture and in vivo implantation study showed that the fiber membranes could kill HepG2 hepatocellular carcinoma cells combined with photothermal-chem and could be enriched in the implantation area, respectively. Hence, the Janus membranes may be a potential cancer treatment material.

Infrared laser moxibustion for cancer-related fatigue in breast cancer survivors: a randomized controlled trial.

BACKGROUND: Cancer-related fatigue (CRF) is a pervasive, persistent, and distressing symptom experienced by cancer patients, for which few treatments are available. We investigated the efficacy and safety of infrared laser moxibustion (ILM) for improving fatigue in breast cancer survivors. METHODS: A three-arm, randomized, sham-controlled clinical trial (6-week intervention plus 12-week observational follow-up) was conducted at a tertiary hospital in Shanghai, China. The female breast cancer survivors with moderate to severe fatigue were randomized 2:2:1 to ILM (n = 56) sham ILM (n = 56), and Waitlist control (WLC)(n = 28) groups. Patients in the ILM and sham ILM (SILM) groups received real or sham ILM treatment, 2 sessions per week for 6 weeks, for a total of 12 sessions. The primary outcome was change in the Brief Fatigue Inventory (BFI) score from baseline to week 6 with follow-up until week 18 assessed in the intention-to-treat population. RESULTS: Between June 2018 and July 2021, 273 patients were assessed for eligibility, and 140 patients were finally enrolled and included in the intention-to-treat analysis. Compared with WLC, ILM reduced the average BFI score by 0.9 points (95% CI, 0.3 to 1.6, P = .007) from baseline to week 6, with a difference between the groups of 1.1 points (95% CI, 0.4 to 1.8, P = .002) at week 18. Compared with SILM, ILM treatment resulted in a non-significant reduction in the BFI score (0.4; 95% CI, -0.2 to 0.9, P = .206) from baseline to week 6, while the between-group difference was significant at week 18 (0.7; 95% CI, 0.2 to 1.3, P = .014). No serious adverse events were reported. CONCLUSION: While ILM was found to be safe and to significantly reduce fatigue compared with WLC, its promising efficacy against the sham control needs to be verified in future adequately powered trials. TRIAL REGISTRATION: Clinicaltrials.gov: NCT04144309. Registered 12 June 2018.

Circumscribing Laser Cuts Attenuate Seizure Propagation in a Mouse Model of Focal Epilepsy.

In partial onset epilepsy, seizures arise focally in the brain and often propagate. Patients frequently become refractory to medical management, leaving neurosurgery, which can cause neurologic deficits, as a primary treatment. In the cortex, focal seizures spread through horizontal connections in layers II/III, suggesting that severing these connections can block seizures while preserving function. Focal neocortical epilepsy is induced in mice, sub-surface cuts are created surrounding the seizure focus using tightly-focused femtosecond laser pulses, and electrophysiological recordings are acquired at multiple locations for 3-12 months. Cuts reduced seizure frequency in most animals by 87%, and only 5% of remaining seizures propagated to the distant electrodes, compared to 80% in control animals. These cuts produced a modest decrease in cortical blood flow that recovered and left a ≈20-µm wide scar with minimal collateral damage. When placed over the motor cortex, cuts do not cause notable deficits in a skilled reaching task, suggesting they hold promise as a novel neurosurgical approach for intractable focal cortical epilepsy.

A Preliminary Study on Quantitative Analysis of Collagen and Apoptosis Related Protein on 1064 nm Laser-Induced Skin Injury.

To investigate the associated factors concerning collagen and the expression of apoptosis-related proteins in porcine skin injuries induced by laser exposure, live pig skin was irradiated at multiple spots one time, using a grid-array method with a 1064 nm laser at different power outputs. The healing process of the laser-treated areas, alterations in collagen structure, and changes in apoptosis were continuously observed and analyzed from 6 h to 28 days post-irradiation. On the 28th day following exposure, wound contraction and recovery were notably sluggish in the medium-high dose group, displaying more premature and delicate type III collagen within the newly regenerated tissues. The collagen density in these groups was roughly 37-58% of that in the normal group. Between days 14 and 28 after irradiation, there was a substantial rise in apoptotic cell count in the forming epidermis and granulation tissue of the medium-high dose group, in contrast to the normal group. Notably, the expression of proapoptotic proteins Bax, caspase-3, and caspase-9 surged significantly 14 days after irradiation in the medium-high dose group and persisted at elevated levels on the 28th day. During the later stage of wound healing, augmented apoptotic cell population and insufficient collagen generation in the newly generated skin tissue of the medium-high dose group were closely associated with delayed wound recovery.

A Workflow for Meaningful Interpretation of Classification Results from Handheld Ambient Mass Spectrometry Analysis Probes.

While untargeted analysis of biological tissues with ambient mass spectrometry analysis probes has been widely reported in the literature, there are currently no guidelines to standardize the workflows for the experimental design, creation, and validation of molecular models that are utilized in these methods to perform class predictions. By drawing parallels with hurdles that are faced in the field of food fraud detection with untargeted mass spectrometry, we provide a stepwise workflow for the creation, refinement, evaluation, and assessment of the robustness of molecular models, aimed at meaningful interpretation of mass spectrometry-based tissue classification results. We propose strategies to obtain a sufficient number of samples for the creation of molecular models and discuss the potential overfitting of data, emphasizing both the need for model validation using an independent cohort of test samples, as well as the use of a fully characterized feature-based approach that verifies the biological relevance of the features that are used to avoid false discoveries. We additionally highlight the need to treat molecular models as "dynamic" and "living" entities and to further refine them as new knowledge concerning disease pathways and classifier feature noise becomes apparent in large(r) population studies. Where appropriate, we have provided a discussion of the challenges that we faced in our development of a 10 s cancer classification method using picosecond infrared laser mass spectrometry (PIRL-MS) to facilitate clinical decision-making at the bedside.

Near-Infrared Light-Excited Quinolinium-Carbazole Small Molecule as Two-Photon Fluorescence Nucleic Acid Probe.

This article reports three new two-photon absorption (TPA) materials that are quinolinium-carbazole derivates. They are 3-(N-methyl-4-ethylquinolinium iodide)-9-ethylcarbazole (M4), 3-(N-methyl-4-ethylquinolinium iodide)-9-ethylcarbazole (H2), and 3-(N-methyl-4-ethylquinolinium iodide)-9-ethylcarbazole (H4). Their TPA cross-sections are 491, 515, and 512 GM, respectively. Under the excitation of near-infrared light, their fluorescence emission is about 650 nm. The compounds can stain nucleic acid DNA with the same level of nuclear localization as Hoechst 33342. Under continuous irradiation with a near-infrared laser, the three new compounds showed less fluorescence decay than DAPI, and the average fluorescence decay rates were 0.016%/s, 0.020%/s, and 0.023%/s. They are expected to become new two-photon fluorescent probes of nucleic acid DNA because of their excellent performance.

Ameliorated Skin Inflammation through the Synergistic Effect of Gold Nanorod-Dexamethasone and Photothermal Therapy.

Psoriasis, a prevalent chronic inflammatory skin ailment affecting approximately 2-3% of the global population, is characterized by persistent symptoms. Dexamethasone, a primary corticosteroid for treating psoriasis, demonstrates notable efficacy; however, its limited skin permeation results in documented adverse effects. To address this, the presented study employed a novel strategy to conjugate gold nanorod and dexamethasone and evaluate their potential for mitigating psoriatic inflammation using an imiquimod-induced mouse model and human skin cells. Our findings revealed enhanced cutaneous penetration of gold nanorod and dexamethasone conjugates compared with that of dexamethasone, owing to superior skin penetration. Gold nanorod and dexamethasone conjugates demonstrated an optimal pharmacological impact at minimal dosages without toxicity during extended use. To further enhance the effectiveness of gold nanorod and dexamethasone conjugates, 808 nm near-infrared laser irradiation, which reacts to gold, was additionally applied to achieve thermal elevation to expedite drug skin penetration. Supplementary laser irradiation at 808 nm significantly ameliorated psoriatic symptoms following deep gold nanorod and dexamethasone conjugates penetration. This corresponded with restored peroxisome proliferator-activated receptor-γ levels and accelerated dexamethasone release from the gold nanorod and dexamethasone conjugates complex. These findings highlight the potential of gold nanorod and dexamethasone conjugates to enhance drug penetration through dermal layers, thereby aiding psoriasis treatment. Moreover, its compatibility with photothermal therapy offers prospects for novel therapeutic interventions across various inflammatory skin disorders.

Temperature and Thermal Diffusivity Diagnostics in Laminar Methane Flames Using Infrared Four-Wave Mixing Techniques.

Four-wave mixing techniques, such as coherent anti-Stokes Raman spectroscopy (CARS), laser-induced grating spectroscopy (LIGS), and degenerate four-wave mixing (DFWM), have been widely used in combustion diagnostics due to their advantages of high signal-to-noise ratio (S/N), coherent signal, and spatial resolution. In this work, a nano-second pulsed laser is utilized to generate mid-infrared (near 3 µm) pump beams, exciting the rovibrational transitions of nascent water in flames. Combined LIGS and DFWM measurements are demonstrated in premixed laminar CH4/O2/N2 flames with equivalence ratios from 0.6 to 1.5, to achieve precise thermometry in a wide range of flame conditions. The flame temperatures were also measured by thermocouple as a reference, and the results from LIGS and DFWM align well with the trends shown in the thermocouple measurements. In fuel-lean flames, where the mass-to-specific-heat ratio variation is minimal, LIGS provides temperature data with a precision better than 16 K (0.8%). In fuel-rich flames, where the increased H2 concentration in the flame introduces uncertainty in gas constants thus affecting the accuracy of LIGS thermometry, DFWM is instead employed for temperature measurement since it is less sensitive to the gas composition within the measured volume. The high-precision LIGS temperatures in lean flames serve as temperature reference during the DFWM calibration of the degree of saturation, and a precision better than 90 K (4.5%) is achieved for DFWM thermometry. In addition to temperature, a theoretical model is employed to fit LIGS signal time waveforms, extracting the local speed of sound and thermal diffusivity with precisions better than 0.5% and 1.3%, respectively. These high-precision measurements contribute additional data for flame research and simulation calculations. This way, the combined use of DFWM and LIGS proves the potential for accurate thermometry and diagnostics of other thermodynamic parameters across a wide range of flame conditions.

A Watt-Level Pulsed Er:Lu2O3 Laser Based on a TiB2 Saturable Absorber.

TiB2 nanoparticles with a bandgap of 0 eV were prepared, and the corresponding nonlinear optical response at 2.85 µm was investigated. Employing a TiB2 as a saturable absorber, a 2.85 µm pulsed Er:Lu2O3 crystal laser with an average output power of 1.2 W was achieved under a maximum pump power of 9.51 W. Laser pulses with durations of ~203 ns were delivered at a repetition rate of 154 kHz, which corresponds to a pulse energy of ~7.8 µJ and a peak power of 39.3 W. As far as we know, the result represents the highest average output power from all Q-switched Er:Lu2O3 crystal lasers.

Evaluation of thermodynamic bioeffects of long-pulsed 1064 nm laser in the photothermal lipolysis.

OBJECTIVES: To evaluate the lipolysis effect of air cooling assisted long-pulsed 1064 laser for improving local adiposity. MATERIALS AND METHODS: The second-level (pulse duration of 0.3-60 s) long-pulsed Nd:YAG 1064 nm laser (LP1064 nm) with or without forced-air cooling was used to irradiate ex-vivo subcutaneous adipose tissue (SAT) of pig or human and in-vivo inguinal fat tissue of Sprague Dawley rats. The temperature of skin surface as well as 5 mm deep SAT was monitored by a plug-in probe thermal couple, and the former was confined to 39°C or 42°C during the treatment. Histological analysis of SAT response was evaluated by SAT sections stained with hematoxylin-eosin and oil red O. Ultra-microstructure changes were examined by transmission electron microscopy. A pilot study on human subject utilizing LP1064 nm laser with air cooling was conducted. The changes in gross abdomen circumference and ultrasonic imaging were studied. RESULTS: Histological examination showed that LP1064 nm laser treatment induced adipocyte injury and hyperthermic lipolysis both in- and ex-vivo. It was also confirmed by clinical practice on patients. By real-time temperature monitoring, we found that in comparison with LP1064 nm laser alone, additional air cooling could increase the temperature difference between epidermis and SAT, promoting heat accumulation deep in fat tissue, as well as providing better protection for epidermis. CONCLUSION: LP1064 nm laser provided reliable adipose tissue thermolysis when the temperature of skin surface was sustained at 39°C or 42°C for 10 min. Application of air-cooling during the laser treatment achieved better effect and safety of photothermal lipolysis. LP1064 nm laser, as a noninvasive device, has comparable thermal lipolysis effect as other common heat-generating devices.

Osteoinductive activity of photobiomodulation in an organotypic bone model.

Photobiomodulation (PBM) is a technique that harnesses non-ionizing light at specific wavelengths, triggering the modulation of metabolic pathways, engendering favourable biological outcomes that reduce inflammation and foster enhanced tissue healing and regeneration. PBM holds significant promise for bone tissue applications due to its non-invasive nature and ability to stimulate cellular activity and vascularization within the healing framework. Notwithstanding, the impact of PBM on bone functionality remains largely undisclosed, particularly in the absence of influencing factors such as pathologies or regenerative therapies. This study aims to investigate the potential effects of PBM using red (660 nm) (RED) and near-infrared (808 nm) (NIR) wavelengths within an ex vivo bone culture system - the organotypic embryonic chicken femur model. A continuous irradiation mode was used, administering a total energy dose of 1.0 J, at an intensity of 100 mW for 10 s, which was repeated four times over the course of the 11-day culture period. The primary focus is on characterizing the expression of pivotal osteoblastic genes, the maturation and deposition of collagen, and the formation of bone mineral. Exposing femora to both RED and NIR wavelengths led to a notable increase in the expression of osteochondrogenic transcription factors (i.e., SOX9 and RUNX2), correlating with enhanced mineralization. Notably, NIR irradiation further elevated the expression of bone matrix-related genes and fostered enhanced deposition and maturation of fibrillar collagen. This study demonstrates that PBM has the potential to enhance osteogenic functionality within a translational organotypic bone culture system, with the NIR wavelength showing remarkable capabilities in augmenting the formation and maturation of the collagenous matrix.

Damage Mechanism of HgCdTe Focal Plane Array Detector Irradiated Using Mid-Infrared Pulse Laser.

To investigate the damage threshold and mechanism of a mid-infrared HgCdTe focal plane array (FPA) detector, relevant experimental and theoretical studies were conducted. The line damage threshold of a HgCdTe FPA detector may be within the range of 0.59 Jcm-2 to 0.71 Jcm-2. The full frame damage threshold of the detector may be in the range of 0.86 Jcm-2 to 1.17 Jcm-2. Experimental results showed that when the energy density reaches 1.17 Jcm-2, the detector exhibits irreversible full frame damage and is completely unable to image. Based on the finite element method, a three-dimensional model of HgCdTe FPAs detector was established to study the heat transfer mechanism, internal stress, and damage sequence. When HgCdTe melts, we think that the detector is damaged. Under these conditions, the theoretical damage threshold calculated using the detector model is 0.55 Jcm-2. The difference between theoretical and experimental values was analyzed. The relationship between damage threshold and pulse width was also studied. It was found that when the pulse width is less than 1000 ns, the damage threshold characterized by peak power density is inversely proportional to pulse width. This relationship can help us predict the experimental damage threshold of an FPA detector. This model is reasonable and convenient for studying the damage of FPA detectors with a mid-infrared pulse laser. The research content in this article has important reference significance for the damage and protection of HgCdTe FPA detectors.