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Terahertz (THz) coherent phonons have emerged as promising candidates for the next generation of high-speed, low-energy information carriers in atomically thin phononic or phonon-integrated on-chip devices. However, effectively manipulating THz coherent phonons remains a significant challenge. In this study, we investigated THz coherent phonon generation in exfoliated van der Waals (vdW) flakes of Fe 3 GeTe 2 , Fe 5 GeTe 2 , and FePS 3 . We successfully generated the THz A 1g coherent phonon mode in these vdW flakes. An innovative approach involved partially exfoliating vdW flakes on a gold substrate and partially on a silicon (Si) substrate to compare the THz coherent phonon generation between both sides. Interestingly, we observed a significantly enhanced THz coherent phonon in the vdW/gold area compared with that in the vdW/Si area. Frequency-domain Raman mapping across the vdW flakes corroborated these findings. Numerical simulations further indicated a stronger enhanced surface field in vdW/gold structures than in vdW/Si structures. Consequently, we attribute the observed enhancement in THz coherent phonon generation to the increased surface field on the gold substrate. This enhancement was consistent across the three different vdW materials studied, suggesting the universality of this strategy. Our results hold promise for advancing the design of THz phononic and phonon-integrated devices.

Purpose: We describe long-term follow-up of a patient with atypical chronic central serous chorioretinopathy with inferior bullous retinal detachment and 360° choroidal detachment, findings on multimodal imaging, differential diagnoses, and treatment., Methods: Case report., Results: A 66-year-old male patient, known case of bilateral chronic central serous chorioretinopathy on follow-up, presented to us with sudden painless worsening of vision in the right eye. The fundus examination, optical coherence tomography, and fundus fluorescein angiography showed an atypical chronic central serous chorioretinopathy with inferior bullous retinal detachment and peripheral choroidal detachment. The patient underwent half-fluence photodynamic therapy in the right eye. At 3 months post-photodynamic therapy, there was resolution of choroidal detachment and minimal subretinal fluid was persisting in the inferior periphery, with improvement in visual acuity., Conclusion: Posterior choroidal loculation of fluid is a described entity in central serous chorioretinopathy. The possible explanations for anterior choroidal loculation of fluid in this case are: either a fresh excessive leakage of fluid from the posterior choroid and that fluid may have traversed to the peripheral choroid, or diffuse choroidal leakage extending up to the equatorial region, which resulted in peripheral choroidal thickening and suprachoroidal fluid accumulation.

Understanding water-soluble and environmentally friendly two-photon absorption (TPA) molecules benefits the design of superior organic complexes for biomedical, illumination, and display applications. In this work, we designed two triphenylamine-based all-organic compounds and explored the mechanism of enhanced TP fluorescence in water solutions for potential applications. Experimentally, we showed that adding protein into our TPA molecule solution can drastically boost the TP fluorescence. Numerical simulations reveal that the TPA molecules prefer to dock inside the protein complex. We hypothesize that the interaction between our triphenylamine-based all-organic compounds and water molecules lead to non-radiative decay processes, which prevent strong TP fluorescence in the water solution. Therefore, the protection by, for example, protein molecules from such interactions can be a universal strategy for superior functioning of organic TPA molecules. Further experiments and numerical simulations support our hypothesis. The present study may facilitate the design of superior water-soluble and environmentally friendly superior organic complexes.

Biofilms pose a significant clinical problem in skin and soft tissue infections. Their resistance to antibiotics has spurred investigations into alternative treatments, such as nanoparticle-mediated photothermal ablation. Non-toxic Hybrid Donor- Acceptor (DA) Polymer nanoParticles (H-DAPPs) were developed for fluorescence imaging (using poly(3-hexylthiophene-2,5 diyl) (P3HT)) and rapid, near-infrared photothermal ablation (NIR- PTA) (using poly[4,4-bis(2-ethylhexyl)-cyclopenta[2,1-b;3,4-b']dithiophene-2,6-diyl-alt-2,1,3-benzoselenadiazole-4,7-diyl] (PCPDTBSe)). H-DAPPs were evaluated alone, and in combination with antibiotics, against planktonic S. aureus and S. pyogenes, and S. aureus biofilms. H-DAPPs NIR-PTA (15-700 μg/ mL) can generate rapid temperature changes of 27.6-73.1 °C, which can eradicate planktonic bacterial populations and reduce biofilm bacterial viability by more than 4- log (> 99.99%) with exposure to 60 s of 800 nm light. Reductions were confirmed via confocal analysis, which suggested that H-DAPPs PTA caused bacterial inactivation within the biofilms, but did not significantly reduce biofilm polysaccharides. SEM imaging revealed structural changes in biofilms after H-DAPPs PTA. S. aureus biofilms challenged with 100 μg/mL of H-DAPPs (H-DAPPs-100) to induce an average temperature of 55.1 °C, and the minimum biofilm eradication concentration (MBEC) of clindamycin, resulted in up to ~3- log decrease in bacterial viability compared to untreated biofilms and those administered H-DAPPs-100 PTA only, and up to ~2- log compared to biofilms administered only clindamycin. This study demonstrates that polymer nanoparticle PTA can mitigate biofilm infection and may improve antimicrobial efficacy., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Two-photon absorption (TPA) enables the excitation of molecules by comparatively lower energy photons with longer penetration depth and higher spatial precision control, which advances the uses of organic molecules in various applications. In this work, we report two simple all-organic molecules C 42 H 33 N (compound 3 ) and C 138 H 168 N 4 (compound 14 ) with strong TPA and fluorescent emission activity. Density functional theory calculations show that the enhanced oscillator strengths could be responsible for improved TPA and emission activity for compound 14 compared to those for 3 . The degradation of C 138 H 168 N 4 under focused laser illumination without circulation is almost negligible within 5 h, making it a candidate for laser dyes. Solid-state measurements confirm the presence of a direct band gap for electron transition that determines the channel to release the absorbed energy and functionality of the studied molecules. This work emphasizes that a high TPA cross-section and selectable energy relaxation (fluorescent emission or heat dissipation) are equally important to the design of advanced functional TPA molecules.

Polymer dynamic organic theranostic spheres (PolyDOTS) are being studied as a photothermal ablation treatment of cancer and are activated by blue or near-infrared light. PolyDOTS or related hybrid polymeric nanoparticle products could be mass-produced, and it is expected that they, like any other engineered nanoparticle (ENP), could be found in aquatic environments. The purpose of this study was to investigate the potential toxicity of these types of hybrid nanoparticles on nontarget marine organisms. To investigate the potential of even greater toxicity due to solar exposure, the PolyDOTS were exposed to the sun for 12 h and "charged". Once charged, hepatopancreas and gill tissues from oysters ( Crassostrea virginica ) were exposed to concentrations of both uncharged and charged PolyDOTS for 24 h in vitro . The effects of PolyDOTS on lysosomal destabilization, cell viability, and free radical damage were analyzed. Significant sublethal toxicity was observed with the charged particles, and reduced viability was observed with uncharged particles in vitro. In vivo imaging studies using IVIS (In Vivo Imaging System) indicated PolyDOTS uptake in tissues. These types of studies are important for understanding the potential effects of light sensitive ENPs in oysters and their broader ecological impacts on estuarine ecosystems.

Purpose: Barrett Universal II (BU-II) is considered as one of the most accurate intraocular lens (IOL) power calculation formulas; however, there is no literature studying the same in Indian population., The Aim of This Study Was to: evaluate the accuracy of BU-II formula in prediction of IOL power for cataract surgery in Asian Indian population., This Was an Institutional,: prospective, observational study., Methods: Patients with senile cataract who underwent phacoemulsification with posterior chamber IOL implantation were enrolled in the study. Biometry data from Lenstar-LS900 was used and IOL power was calculated using four IOL formulas: modified SRK-II, SRK/T, Olsen, and BU-II. Primary outcome was measured as the prediction error in postoperative refraction for each formula and secondary outcome was measured as the difference in mean absolute errors between the four formulas. SPSS Version-21 with P < 0.05 considered significant., Results: A total of 244 eyes were included in the study and were divided into three groups in accordance to axial length (AL): Group 1 (AL: 22-24.5 mm; N = 135), Group 2 (AL <22 mm; N = 53), and Group 3 (AL >24.5 mm; N = 56). BU-II formula gave the lowest mean absolute error (0.37 ± 0.27D) and median absolute error (0.34) in predicted postoperative refraction in the entire study population. When compared with the other formulas, mean absolute error was significantly lower in all three groups (P < 0.0005) as well, except for Olsen formula in the normal AL group, where the results were comparable (P = 0.742)., Conclusion: BU-II performed as the most accurate formula in the prediction of postoperative refraction over a wide range of ALs., Competing Interests: None

Judicious combination of semiconducting polymers with alternating electron donor (D) and acceptor (A) segments created hybrid nanoparticles with amplified energy transfer and red-shifted emission, while simultaneously providing photothermal capabilities. Hybrid D-A polymer particles (H-DAPPs) passively localized within orthotopic breast tumors, serving as bright fluorescent beacons. Laser stimulation induced heat generation on par with gold nanorods, resulting in selective destruction of the tumor. H-DAPPs can also undergo multiple thermal treatments, with no loss of fluorescence intensity or photothermal potential. These results indicate that H-DAPPs provide new avenues for the synthesis of hybrid nanoparticles useful in localized detection and treatment of disease.

Poly(glycerol sebacate) (PGS)/nanohydroxyapatite (nHA) composites were assessed to develop new materials for closure via tissue transport for nonhealing defects (e.g., cleft palate and large skin wounds). The elastic shape memory polymer, PGS, was reinforced with nHA at 3 and 5% loading to increase the mechanical properties compared with the undoped PGS. Differential scanning calorimetry (DSC) was utilized to identify a glass transition temperature (Tg ) of -25°C. X-ray diffraction demonstrated a reduction in the amorphous nature of the material. The Fourier transform infrared photoacoustic spectral (FTIR-PAS) data showed decreased CO bonding and increased hydrogen bonding with increased nHA incorporation. Composites exhibited Young's moduli in the range of 0.25-0.5 MPa and tensile strength of 1.5-3 N. No significant difference in extension to break (∼50 mm) with addition of nHA was observed. The elastic modulus significantly increased for 5% PGS/nHA compared to 0 and 3% PGS/nHA and tensile strength significantly increased for 3% PGS/nHA compared to 0 and 5% PGS/nHA. Degradation of 5% nHA/PGS significantly increased during the second week compared to PGS 0 and 3% PGS/nHA. The accelerated degradation for 5% PGS/nHA coupled with decreased flexibility and tensile strength implies an interruption in crosslinking. By maintaining flexibility and extension while increasing tensile strength, the 3% PGS/nHA doped satisfied the force range desired for closure of soft tissue defects. Based on this work, PGS with 3% nHA shape memory polymers should serve as a good candidate for closure of nonhealing soft tissues. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1366-1373, 2016., (© 2015 Wiley Periodicals, Inc.)

Chitosan films were synthesized with hexagonal silver nanoparticles (Ag NP). The unique shape and size of the Ag NP shift the optical absorption into the infrared. Stimulation of the nanoparticles with infrared light was used to generate heat and facilitate intracellular delivery of fluorescently-labeled dextran molecules. Chitosan films prepared with hexagonal or spherical Ag NP were characterized by optical and thermal analyses, and X-ray diffraction. There were found to be slight differences between how the chitosan molecular chains interface with the Ag NP depending upon shape of the nanoparticle. Viability of cells associated with dermal wound healing was evaluated on chitosan films prepared with hexagonal or spherical Ag NP, with both keratinocytes and fibroblasts having normal or moderately enhanced growth on films containing hexagonally-shaped nanoparticles., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Development of resorbable elastic composites as an alternative means to apply contractive forces for manipulating craniofacial bones is described herein. Composites made from the biodegradable elastomer, poly (1,8-octanediol co-citric acid) (POC), and hydroxyapatite (nHA) with a 200 nm diameter (0-20% loadings) were created to develop a material capable of applying continuous contractive forces. The composites were evaluated for variation in their mechanical properties, rate of degradation, and interaction of the hydroxyapatite nanoparticles with the polymer chains. First, an ex vivo porcine model of cleft palate was used to determine the rate of cleft closure with applied force. The closure rate was found to be 0.505 mm N(-1) . From this approximation, the ideal maximum load was calculated to be 19.82 N, and the elastic modulus calculated to be 1.98 MPa. The addition of nHA strengthens POC, but also reduces the degradation time by 45%, for 3% nHA loading, compared to POC without nHA. X-ray diffraction data indicates that the addition of nHA to amorphous POC results in the formation of a semicrystalline phase of the POC adjacent to the nHA crystals. Based on the data, we conclude that amongst the 0-20% nHA loadings, a 3% loading of nHA in POC may be an ideal material (1.21 MPa elastic modulus and 13.17 N maximum load) to induce contraction forces capable of facilitating osteogenesis and craniofacial bone repair., (© 2014 Wiley Periodicals, Inc.)

Optical properties of cadmium sulfide nanowires of 50-100 nm diameter prepared by the pulsed-laser vaporization method have been studied using photoacoustic, UV-Vis, Raman, and photoluminescence spectroscopy. The photoacoustic (PA) technique yielded clean spectra with a steeper absorption edge for as-prepared opaque semiconducting CdS nanowires when compared to the corresponding conventional optical absorption spectra. The PA signal intensity was also significantly higher for nanowires. The Raman spectrum revealed increased exciton-longitudinal-optical-phonon coupling. The appearance of a narrow photoluminescence peak at 491 nm (FWHM approximately 9 nm) and the absence of emission above 500 nm demonstrate the high quality of nanowires. High-resolution transmission electron microscopy showed excellent ordering of the atoms in the [001] planes perpendicular to the growth direction.

Photo-formation of gold nanoparticles in the solid monoliths of Au(III)-chitosan-silica aerogels with different Au/NH(2) molar ratios has been investigated using photoacoustic spectroscopy. Upon exposing to 320 nm UV light, a new absorption feature in the visible region around 525 nm could be seen due to the surface plasmon resonance of gold particles that are generated as a result of UV-induced reduction of Au(III) to Au(0). The plasmon band becomes stronger and shows saturation effects upon increasing the UV exposure time. A blue shift of about 7 nm is also noticed on exposing the sample (Au/NH(2)=1/5) for 6h, indicating a slight decrease in the nanoparticle size due to light-induced annealing with increasing the UV exposure time. The PA signals monitored as a function of chopping frequency show omega(-1) dependence, implying the thermally thin character of Au(III)-chitosan-silica aerogels.

The early stages of the ring opening reaction of 1,3-cyclohexadiene to form its isomer 1,3,5-hexatriene, upon excitation to the ultrashort-lived 1 1B2 state, were explored. A series of one-color two-photon ionization/photoelectron spectra reveal a prominent vibrational progression with a frequency of 1350 cm(-1), which is interpreted in a dynamical picture as resulting from the ultrafast wave packet dynamics associated with the ring opening reaction. Photoionization in two-color three-photon and one-color four-photon ionization schemes show an ionization pathway via the same ultrashort-lived 1 1B2 state, and in addition, a series of Rydberg states with quantum defects of 0.93, 0.76, and 0.15, respectively. Using those Rydberg states as probes for the reaction dynamics in a time-resolved pump-probe experiment provides a direct observation of the elusive 2 1A1 state that has been implicated as an intermediate step between the initially excited 1 1B2 state and the ground electronic state. The rise and decay times for the 2 1A1 state were found to be 55 and 84 fs, respectively.

Local photoionization pathways and charge-transfer dynamics of 2-phenylethyl-N,N-dimethylamine (PENNA) are explored using the recently developed Rydberg fingerprint spectroscopy. PENNA, a molecule that derives its biological significance from its relation to neurotransmitters, has two ionization centers that are separated by an ethyl group. We ionize the molecule in various multiphoton ionization processes using different laser wavelengths. The Rydberg fingerprint spectrum reveals the local nature of the ionization process and identifies the center of charge. We discovered that the laser wavelength provides substantial control over the activation of the individual ionization centers. The resonant (2+1) ionization with 400-nm radiation is dominated by the ejection of an electron from the amine moiety. In contrast, the resonant (1+1) ionization with 266-nm radiation leads predominantly to an ion with the charge in the phenyl group. The clean separation of the two ionization processes allows the exploration of ultrafast charge-transfer dynamics ensuing from a specific starting state characterized by a charged phenyl moiety. The width of the corresponding spectral features suggests that the charge transfer proceeds on a femtosecond time scale, suggesting a strong coupling between the two lowest-energy electronic surfaces of the PENNA cation.