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Photo-physical properties of substituted 2,3-distyryl indoles: Spectroscopic, computational and biological insights
摘要： The structural dependence of the photo-physical properties of substituted 2,3-distyryl (23DSI) indoles were studied using several spectroscopic techniques including steady-state UV-VIS spectroscopy, steady-state fluorescence spectroscopy, steady-state excitation spectroscopy, time correlated single photon counting (TCSPC) spectroscopy, and time-resolved fluorescence upconversion spectroscopy (TRFLS). Each of 23DSI derivatives investigated showed distinct fluorescence emission and UV-VIS spectra, indicating strong structural dependence of the emission and the excitation. The UV-VIS spectra of the 23DSI derivatives showed three main identical absorption bands with minor deviations in the absorbance caused by substituent groups on the distyryl rings. The time-resolved fluorescence up-conversion studies indicated that the fluorescence undergoes a mono-exponential decay whereas the calculated fluorescence lifetime showed relatively short fluorescence lifetimes of approximately 1 ns. All of the 23DSI derivatives showed two-photon absorption upon direct excitation of 1.6 W laser pulses at 800 nm. These studies suggest that the substituents, attached to distyryl core, are capable of boosting or hindering fluorescence intensities by distorting the π-conjugation of the 23DSI molecule. Our studies showed that 23DSI (p-F) has the highest fluorescence emission quantum yield. Theoretical calculations for the ground state of 23DSI derivatives confirmed differences in electron densities in 23DSI derivatives in the presence of different substituent attachments. The excellent fluorescence emission, high fluorescence quantum yield and two-photon absorption properties of these 23DSI molecules make them attractive candidates for potential applications in the fields of biological imaging, biomedicine, fluorescent probes, and photodynamic inactivation (PDI). B. subtilis samples, treated with micro molar solutions of 23DSI (p-OCH3) and 23DSI (p-CH3), showed very effective photodynamic inactivation (PDI) upon irradiation with white light.
关键词： Two photon absorption,Time-resolved fluorescence upconversion laser spectroscopy,Photodynamic inactivation,Gaussian calculations,Photo-physical properties,Light-activation
更新于2025-11-14 15:26:12
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ZnO Micro- and Nanostructures Obtained by Thermal Oxidation: Microstructure, Morphogenesis, Optical, and Photoluminescence Properties
摘要： ZnO micro- and nanostructures were obtained through thermal oxidation of Zn powders at high temperature under air atmosphere. A detailed study of the microstructure, morphology, optical, and photoluminescence properties of the generated products at different stages of thermal oxidation is presented. It was found that the exposure time has a strong influence on the resulting morphology. The morphogenesis of the different ZnO structures is discussed, and experimental parameters for fabricating ZnO tetrapods, hollow, core-shell, elongated, or rounded structures by thermal oxidation method are proposed on the basis on the obtained results. Notoriously, the crystal lattice of the ZnO structures has negligible residual strain, although, the density of point defects increases when the thermal treatment is extended; as consequence, their visible luminescence upon UV excitation enhances.
关键词： growth mechanism,ZnO structures,thermal oxidation,physical properties
更新于2025-09-23 15:23:52
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Diversity of physical properties of bacterial extracellular membrane vesicles revealed through atomic force microscopy phase imaging
摘要： Bacteria release nanometer-scale extracellular membrane vesicles (MVs) to mediate a variety of biological processes. We analyzed individual MVs under physiological conditions by phase imaging of high-speed atomic force microscopy to assess the physiological heterogeneity of MVs isolated from bacterial cultures. Phase imaging makes it possible to map the physical properties of an individual, fragile MV in an isolated MV population containing a broad variety of vesicle diameters, from 20 to 150 nm. We also developed a method for quantitatively comparing the physical properties of MVs among samples. This allowed for the comparison of the physical properties of MVs isolated from different bacterial species. We compared bacterial MVs isolated from four bacterial species and artificially synthesized liposomes. We demonstrate that each bacterial species generates physically heterogeneous types of MVs, unlike the physical homogeneity displayed by liposomes. These results indicate that the physical heterogeneity of bacterial MVs is mainly caused by compositional differences mediated through biological phenomena and could be unique to each species. We provide a new methodology using phase imaging that would pave the way for single-vesicle analysis of extracellular vesicles of a broad size range.
关键词： heterogeneity,atomic force microscopy,physical properties,phase imaging,bacterial extracellular membrane vesicles
更新于2025-09-23 15:21:01
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Effect of light absence or attenuation on biaxial flexural strength of dual-polymerized resin cements after short- and long-term storage
摘要： Objective: To evaluate whether biaxial flexural strength (BFS) of dual resin cements is affected by light absence or attenuation, storage time, or cements' chemical nature. Materials and methods: One hundred and twenty disk-shaped specimens were made from each cement (non-self-adhesive cement and self-adhesive cement) using Teflon molds on a controlled temperature surface (35°C). Specimens were polymerized as follows (N = 30): self-cured, directly light-cured, light-cured at a distance of 6 mm between the light tip and the specimen, and through a 6-mm thick composite resin barrier (indirectly light-cured). Each group was divided (N = 10) for storage purposes (15 minutes, 24 hours, and 6 months). Specimens were placed into a biaxial-flexure jig and a vertical load was applied until failure. The BFS values were subjected to generalized linear models statistical analysis and Weibull distributions (α = 0.05). Results: After 15 minutes aging, neither material achieved enough polymerization to perform the BFS test when polymerized using the self-curing mode. The self-adhesive product demonstrated much lower variation in strength with storage time than did the non-self-curing cement. Conclusions: Attenuated/light-curing reduced BFS values only for 15-minutes storage period for both materials. Flexural strength of the self-adhesive cement was less affected by light absence/attenuation and storage time.
关键词： resin cements,Weibull analysis,biaxial flexural strength,physical properties,polymerization
更新于2025-09-23 15:21:01
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Carbons dots: The next generation platform for biomedical applications
摘要： Among the wide range of carbon family nanomaterials, carbon dots (CDs) one of the promising candidate which have attracted tremendous attention due to its unique advantages such as facile synthesis procedure, easy surface functionalization, outstanding water solubility, low toxicity and excellent photo-physical properties. Due to these unique advantages, CDs are extensively used in catalysis, electronics, sensing, power as well as in biological sectors. In this review we will discuss recent progress in synthesis, structure and fluorescence properties of CDs with special highlight on its biomedical applications, more precisely we will highlight on CDs, for drug/gene delivery, bioimaging and photothermal and photodynamic therapy applications. Furthermore, we discuss the current challenges and future perspective of CDs in the field of biomedical sector.
关键词： Photo-physical properties,Bioimaging,Photothermal and photodynamic therapy,Drug/gene delivery
更新于2025-09-23 15:21:01
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Impact of Hydrogen flow rate on physical properties of ZnS thin films: As potential buffer layer in solar cells
摘要： The exceptional need of potential Cd-free buffer layer in thin film solar cell devices motivated us to study the role of post-deposition Hydrogen annealing for the optimization of physical properties of ZnS thin films. The deposited films of thickness 200 nm were hydrogenated within the flow rate range of 50.0–150.0 sccm at 200°C. XRD analysis revealed transformation of amorphous into cubic phase with maximum crystallinity at 150.0 sccm for films deposited on glass substrate while into wurtzite structure for films on ITO substrate with enhanced crystallinity. A mixed phase (cubic and hexagonal) at 150.0 sccm also appeared. Electrical behaviour (I–V) exhibits ohmic nature with maximum carrier concentration at 100.0 sccm. The blue shift in absorption edge and maximum of 95% transmittance were recorded in the visible region with optical energy band gap of 3.41 eV at 150.0 sccm. The reduction in surface roughness is observed in surface topographical analysis while the photoluminescence (PL) study indicated a sharp peak at 2.95 eV with strongest emission for 150.0 sccm attributed to reduction of defects at interstitial sites and passivation of grain boundaries. These results are useful to understand the Hydrogen related impurities in ZnS films and the improvement caused by hydrogenation to physical properties suited for buffer layer in solar cells.
关键词： Buffer layer,ZnS thin films,Hydrogenation,Physical properties,e-beam evaporation
更新于2025-09-23 15:19:57
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[Advances in Food and Nutrition Research] || Advanced Analysis of Roots and Tubers by Hyperspectral Techniques
摘要： Hyperspectral techniques in terms of spectroscopy and hyperspectral imaging have become reliable analytical tools to effectively describe quality attributes of roots and tubers (such as potato, sweet potato, cassava, yam, taro, and sugar beet). In addition to the ability for obtaining rapid information about food external or internal defects including sprout, bruise, and hollow heart, and identifying different grades of food quality, such techniques have also been implemented to determine physical properties (such as color, texture, and specific gravity) and chemical constituents (such as protein, vitamins, and carotenoids) in root and tuber products with avoidance of extensive sample preparation. Developments of related quality evaluation systems based on hyperspectral data that determine food quality parameters would bring about economic and technical values to the food industry. Consequently, a comprehensive review of hyperspectral literature is carried out in this chapter. The spectral data acquired, the multivariate statistical methods used, and the main breakthroughs of recent studies on quality determinations of root and tuber products are discussed and summarized. The conclusion elaborates the promise of how hyperspectral techniques can be applied for non-invasive and rapid evaluations of tuber quality properties.
关键词： Gradation,Physical properties,Chemometric analyses,Multivariate statistics,Hyperspectral imaging,Chemical constituents,Authentication,Vibrational spectroscopy,Potato tuber,Food quality
更新于2025-09-19 17:15:36
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Estimating physical properties from liquid crystal textures via machine learning and complexity-entropy methods
摘要： Imaging techniques are essential tools for inquiring a number of properties from different materials. Liquid crystals are often investigated via optical and image processing methods. In spite of that, considerably less attention has been paid to the problem of extracting physical properties of liquid crystals directly from textures images of these materials. Here we present an approach that combines two physics-inspired image quantifiers (permutation entropy and statistical complexity) with machine learning techniques for extracting physical properties of nematic and cholesteric liquid crystals directly from their textures images. We demonstrate the usefulness and accuracy of our approach in a series of applications involving simulated and experimental textures, in which physical properties of these materials (namely: average order parameter, sample temperature, and cholesteric pitch length) are predicted with significant precision. Finally, we believe our approach can be useful in more complex liquid crystal experiments as well as for probing physical properties of other materials that are investigated via imaging techniques.
关键词： machine learning,physical properties,image analysis,complexity-entropy methods,liquid crystals
更新于2025-09-19 17:15:36
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Luminescence Properties of Dy3+ and Sm3+: Potassium Lithium Borate Glass
摘要： The present paper describes the spectral properties of Sm3+ (0.4 mol%) and Dy3+ (0.4 mol%) ions-doped 20Li2O–10K2O–70B2O3 glasses. X-ray diffraction method was use to confirm the amorphous phase of samples. The physical properties have been determined based on UV absorption spectra. The hypersensitive transition of Dy3+ and Sm3+ is found due to transition of (6F11/2,6H9/2) and (6F7/2), respectively. The emission bands of Dy3+: glass has shown around 572 nm, 612 nm and 646 nm; these emissions are attributed to the transitions of 4F9/2 →6H15/2 (yellow), 4F9/2 - 6H13/2 (red) and 4F9/2 -6H11/2 (red). With regard to Sm3+: glass has three emission bands those have been generated from 4G5/2 → 6H5/2 (616 nm), 4G5/2 → 6H 7/2 (660 nm) and 4G5/2 → 6H9/2 (719 nm) transitions. The current results promise several applications in optical fields such as UV-sensor, developing new color light sources and tunable visible lasers.
关键词： physical properties,rare-earth ions,luminescence,Glasses
更新于2025-09-19 17:15:36
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Enhanced solar cell performance of P3HT:PCBM by SnS nanoparticles
摘要： In this research, un- and zinc (Zn)-doped tin sulfide (SnS) nanoparticles (NPs) were synthesized by ultrasound method and added to the active layer of ITO/PEDOT:PSS/P3HT: PCBM/Al polymer solar cells (PSCs). The structural, optical, and electrical properties due to the influence of NPs on solar cell performance were investigated. The X-ray diffraction (XRD) patterns of the NPs indicates the formation of orthorhombic polycrystalline SnS. Field emission scanning electron microscopy (FESEM) images show spherical particles with size less than 100 nm for un- and Zn-doped SnS samples. Optical analysis of the cells shows a decrease in the band gap due to the presence of un- and Zn-doped SnS NPs. Photovoltaic characterization of the samples shows that by adding NPs to the polymer film, the device performance improves significantly compared to the absence of NPs. The presence of NPs with different concentrations and structural defects affects the electro-optical properties of the samples.
关键词： P3HT:PCBM,Polymer solar cells,Tin sulfide nanoparticles,Physical properties
更新于2025-09-19 17:13:59