Search

Red-light-emitting InP/ZnSexS1-x core/shell quantum dots (QDs) were prepared by one-pot synthesis with optimal hydrogen fluoride (HF) treatment. Most of the surficial oxidative species could be removed, and the dangling bonds would be passivated by Zn ions for the InP cores during HF treatment, which would be beneficial to the subsequent ZnSexS1-x shell coating. Three-dimensional time-resolved photoluminescence spectra of the QD samples were analyzed by singular value decomposition global fitting to determine the radiative and nonradiative lifetimes of charge carriers. A proposed model illustrated that the charge carriers in the InP/ZnSexS1-x QDs with interfacial oxidative layer removal would evidently recombine through radiative pathways, mainly from the conduction band to the valence band (lifetime, 33 ns) and partially from the trap states (lifetime, 150 ns). This work offers the important physical insight into the charge carrier dynamics of low-toxicity QDs which have the desired optical properties for optoelectronic applications.

In this study, a 10&ndash, 50 nm Co32Fe30W38 alloy thin film sputtered on glass substrates was annealed at different temperatures for 1 h including room temperature (RT), 300, 350, and 400 &deg, C. The structure, magnetic properties, surface energy, and optical properties of the Co32Fe30W38 alloy were studied. X-ray diffraction (XRD) patterns of the as-deposited Co32Fe30W38 thin films showed the amorphous structure. The apparent body-centered cubic (BCC) CoFe (110) structure was exhibited after 300 &deg, C annealing for 1 h. The 300 &deg, C annealed Co32Fe30W38 thin film showed the highest CoFe (110) peak compared with other temperatures. Furthermore, the thicker the Co32Fe30W38 thin film, the higher the CoFe (110) peak. The CoFe (110) peak revealed magneto-crystalline anisotropy, which was related to the strong low-frequency alternative-current magnetic susceptibility (&chi, ac) and induced an increasing trend of saturation magnetization (Ms) as the thickness (tf) increased. Due to the thermal disturbance, the &chi, ac and Ms for the 350 and 400 &deg, C annealed Co32Fe30W38 thin film decreased. The contact angles of the Co32Fe30W38 thin films were less than 90&deg, For all temperatures, the surface energy increased when the film thickness increased from 10 to 50 nm. In addition, the surface energies for annealed samples were comparatively higher than the as-deposited samples. The higher surface energy of 28 mJ/mm2 was obtained for the 50 nm Co32Fe30W38 thin film annealed at 300 &deg, C. The transmittance percentage (%) of the as-deposited Co32Fe30W38 film was higher than other annealed conditions. This result contributed to the fact that higher crystallization, due to perfect band structures, may inhibit the transmission of photon signals through the film, resulting in low transmittance and high absorption.

The applications of piezoelectric nanogenerators (PENGs) as a sustainable power source for portable electronic devices are still limited due to low voltage output ranging from mini- to several volts. In this study, we first develop a porous ZnO structure by annealing (650–950 °C) sputtered ZnO thin film. The porous ZnO thin film enables a significant enhancement in the output voltage of primitive PENG (up to 3 mV), i.e., by 7.5 times than that of pristine ZnO (0.4 mV). Concurrently, the introduction of pores in ZnO thin films leads to a 6.9-fold enhancement in the sensitivity of piezotronic force sensor compared to the pristine one. These excellent performances are further supported by up to two-fold enhancement in the piezoelectric coefficient (2.62 pm/V) than that of pristine ZnO (1.12 pm/V). Herein, we conducted transmission electron microscopy characterizations and found that this phenomenon can be ascribed to the lattice contraction in the c-direction induced by the pores. The diffusion-controlled pore formation mechanism is elucidated.

A graphene quantum dot (GQD) used as the photosensitizer with high two-photon absorption in the near-infrared region, a large absolute cross section of two-photon excitation (TPE), strong two-photon luminescence, and impressive two-photon stability could be used for dual modality two-photon photodynamic therapy (PDT) and two-photon bioimaging with an ultrashot pulse laser (or defined as TPE). In this study, a GQD efficiently generated reactive oxygen species coupled with TPE, which highly increased the effective PDT ability of both Gram-positive and -negative bacteria, with ultralow energy and an extremely short photoexcitation time generated by TPE. Because of its two-photon properties, a GQD could serve as a promising two-photon contrast agent for observing specimens in depth in three-dimensional biological environments while simultaneously proceeding with PDT action to eliminate bacteria, particularly in multidrug-resistant (MDR) strains. This procedure would provide an efficient alternative approach to easily cope with MDR bacteria.

d -Panthenol (provitamin B5) and salt of pantothenic acid are used in many cosmetic and pharmaceutical preparations for their skin emollient, regenerating and hair conditioning properties. The cathodic reduction of d -panthenol and salt of pantothenic acid had been studied by differential pulse voltammetry (DPV) at carbon paste electrode (CPE) and metal oxides modified CPE in the presence of cationic surfactants (stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, dodecyltrimethylammonium chloride), anionic surfactants (sodium dodecyl sulfate, sodium dodecyl ether sulfate, sodium dodecylbenzenesulfonate) and non-ionic surfactants (TritonX-100, Span 60 and Tween 60) micelles. The peak potentials and peak currents have been found to be dependent on the character and concentration of the surfactant. The reduction potential of d -panthenol at a cobalt oxide modified CPE is shifted by 220 mV to more positive potential in the presence of the stearyltrimethylammonium chloride micelle. d -Panthenol and salt of pantothenic acid in commercial cosmetic and pharmaceutical preparations were determined by DPV using a cobalt oxide modified CPE in phosphate buffer (pH 6.08) solution. Comparison with results obtained from the spectrophotometry (SPM) shows good agreement.

The effect of surface plasmon resonance (SPR) on the blinking emission of photoluminescence from noble metal nanostructures still requires further investigation in quantum mechanics and limits their applications. We investigate one photon luminescent emission intermittency of noble metal nanostructures with differently sized sea-urchin-shaped nanoparticles, known as nano-sea-urchins (NSUs). The probability of the “on” process in one photon luminescent emission intermittency of NSUs increases due to the strong electric field of SPR. This mechanism is explained by the reaction potential threshold model we propose here. Furthermore, the ameliorated photoluminescence of NSUs is strong enough to excite waterweed bioluminescence and can act as an in vivo bio-light emitting device, which has potential applications in cytotoxicity, bio-imaging and bio-labeling.

Colorectal carcinoma is a human malignant tumor, which is very resistant to currently available methods of treatment. Therefore, developing an effective agent with anti-colorectal carcinoma activity is important. In the present study, 8 structurally related flavones including flavone, 3-OH flavone, 5-OH flavone, 7-OH flavone, quercetin, kaempferol, quercetin, and morin were used to study their effects on colorectal carcinoma cells (HT29, COLO205, COLO320-HSR). Results of MTT assay indicated that flavone shows the most potent cytoxic effect among them on these three cell types. The cytotoxicity induced by flavone is mediated by inducing the occurrence of apoptosis characterized by the appearance of DNA ladders, apoptotic bodies and hypodiploid cells. Activation of caspase 3 protein procession and enzyme activity with inducing cleavage of caspase 3 substrates PARP was identified in flavone-treated cells, and an inhibitory peptide Ac-DEVD-FMK for caspase 3, but not Ac-YVAD-FMK for caspase 1, attenuates the cytotoxic effect of flavone in COLO205 and HT29 cells. Elevation of p21 but no p53 protein was observed in flavone-treated cells. Increasing intracellular peroxide level was detected in flavone-treated cells by DCHF-DA assay, and antioxidants such as tiron, catalase, SOD, PDTC, but not DPI, suppress flavone-induced cytotoxic effect. In vivo anti-tumor study indicates that flavone exhibits ability to inhibit tumor formation elicited by s.c. injection of COLO205 cells in nude mice, and apoptotic cells and an increase in p21, but not p53, protein were observed in tumor tissues derived from flavone-treated group. Additionally, flavone induced apoptosis in primary colon carcinoma cells COLO205-X with appearance of DNA ladders, caspase 3 protein procession, PARP protein cleavage, and an increase in p21 (not p53) protein. These data provide evidence to suggest that flavone is an effective agent to induce apoptosis in colorectal carcinoma cells in vitro and in vivo; activation of caspase 3, ROS production, and increasing p21 protein are involved.