Increase Of Illumination Time Research Articles

Controllable surface-initiated metal-free atom transfer radical polymerization of methyl methacrylate on mesoporous SBA-15 via reductive quenching

The surface-initiated metal-free atom transfer radical polymerization (ATRP) solution polymerization of methyl methacrylate was carried out for the first time on the basis of the reductive quenching mechanism. In this study, the 2-bromoisobutyryl bromide (BiBB) was anchored on the surface of self-synthesized rod-like mesoporous material SBA-15 as the initiator, with the commercially available organic dye fluorescein (FL) as photocatalyst and triethylamine (TEA) as electron donor under the irradiation of blue lamp. The obtained composites and polymers were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, N2 adsorption/desorption measurements, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and gel permeation chromatography. The results demonstrated that the ordered mesoporous structure of SBA-15 was not disrupted after the polymerization. With an increase in illumination time, the grafting amount and the number average molecular weight of poly(methyl methacrylate) (PMMA) on the surface of SBA-15 linearly increased, and the molecular weight distribution (Đ) widened. PMMA with a relatively narrow Đ value was obtained after polymerization for 10 h (1.47). The increase in the grafting amount and molecular weight after chain extension confirmed the chain end functionality of PMMA grafted on SBA-15.

Study on Preparation of Microlens Array Hydrophobic Flim by Ultraviolet Curing Micro-imprint

In this paper, the formation process of microstructure array hydrophobic film prepared by ultraviolet curing imprinting was studied. The UV-curing micro-imprinting method was used to replace the traditional hot stamping method to prepare the micro-structured hydrophobic film. The effects of illumination time and intensity on the surface hydrophobicity were investigated.Results shown that the micro-structure hydrophobic film prepared by UV-curing micro-imprint has high replication precision and good hydrophobic effect. With the increase of illumination time, the water contact angle of the product increased and reached to 125° at 30s illumination time. With the increase of the illumination intensity, the water contact angle of the micro-imprinted product was also gradually increased.

High photocatalytic degradation efficiency of oxytetracycline hydrochloride over Ag/AgCl/BiVO4 plasmonic photocatalyst

A series of ternary Ag/AgCl/BiVO4 photocatalysts with different UV light reduction time were synthesized. All the samples were investigated and characterized by XRD, XPS, SEM, PL and so on. The results of UV–Vis DRS and PL demonstrated that the ternary photocatalysts exhibited higher absorption in visible light region. And from the XRD patterns, it could be inferred that with the increase of illumination time, the content of metallic Ag on the surface of ternary photocatalysts increased. In the ternary photocatalyst system, Ag nanoparticles acted as the electron mediator and induced the surface plasmon resonance to facilite the photocatalytic activity of as-obtained ternary photocatalysts. During the photocatalytic degradation of oxytetracycline hydrochloride, the 1 h-Ag/AgCl/BiVO4 photocatalyst showed the best degradation activity, and the main active species participating in the reaction were holes and superoxide radicals. According to the experimental results, the 1 h-Ag/AgCl/BiVO4 photocatalyst exhibited excellent stability and effectively degraded OTC under a wide pH range condition or co-existing ions. The experimental results provided a scientific basis for the practical application of the 1 h-Ag/AgCl/BiVO4 photocatalyst, especially for the treatment of antibiotics in the water.

The influence of illumination on two-photon absorption of quantum dots

The influence of illumination with 365[Formula: see text]nm ultraviolet light on two-photon absorption (TPA) of aqueous Co[Formula: see text] doped CdTe (CdTe:Co) quantum dots (QDs) is studied. The results show that with the increase of illumination time, the TPA cross section of the CdTe:Co QDs increases. The experimental results suggest that this enhancement is due to the reduction of surface nonradiative traps which is consistent with the formation of CdS shell on the surface of CdTe:Co QDs. Meanwhile, the results indicate that aqueous CdTe:Co QDs have good optical limiting and optical stabilization performances. This provides a strategy of TPA enhancement by illumination.

Light-Driven Transformation of Bio-Inspired Superhydrophobic Structure via Reconfigurable PAzoMA Microarrays: From Lotus Leaf to Rice Leaf

Light-driven transformation from isotropic superhydrophobicity to anisotropic superhydrophobicity was accomplished through bio-inspired modification and reconfiguration on poly[6-(4-methoxy-4′-oxyazobenzene)hexyl methacrylate] (PAzoMA) microarrays. In this study, ordered PAzoMA microarray film was fabricated via the reverse breath figure (RBF) method. After gold nanoparticles sputtering and subsequent modification with self-assembly of 1H,1H,2H,2H-perfluorodecanethiol (FSH), the obtained lotus-leaf-inspired film showed isotropic superhydrophobicity with self-cleaning property due to the hierarchical structure and low surface free energy. Upon irradiation with linearly polarized light (LPL), the microspheres were elongated along the direction of polarization and exhibited anisotropic superhydrophobicity resembling rice leaf. With the increase of illumination time, the axis ratio became larger, and anisotropy sliding was more obvious. This research enriches responsive bio-inspired superhydrophobicity and fu...

A study on photo-induced crystallization in Ga10Se78Tl12 thin films

This paper reports the photo-induced crystal- lization in glassy Ga10Se78Tl12 thin films. The glassy na- ture of the bulk material was confirmed by non-isothermal differential scanning calorimetry measurements. The pho- to-induced crystallization in Ga10Se78Tl12 films was done by exposing to light (using 2000 W tungsten lamp) at various illumination times under the fixed ambient tem- perature at 358 K. Virgin and photo-induced Ga10Se78Tl1 thin films were characterized by X-rays diffraction, scan- ning electron microscopy, optical and electrical measure- ments. The photo-induced crystallization is associated to the change in structure of Ga10Se78Tl12 thin films which initiated the significant change in the optical constants. The detailed examination of the optical absorption results indicated that the optical transition was indirect. The op- tical band gap of Ga10Se78Tl12 thin films were decreased while the absorption and the extinction coefficients in- creased with the increase of illumination time. From dark conductivity results, the dark conductivities of thin films continuously heightened and the activation energy turned to be lower as increasing the illumination time. The low- ering in optical band gap and activation energy might be due to the occurrence of photo crystallization with the in- crement of illumination time.

Studies of the interaction of CS@ZnS:Mn with bovine serum albumin under illumination

In this study, chitosan coated Mn-doped ZnS quantum dots (CS@ZnS:Mn D-dots) were obtained in aqueous media under ambient pressure. The interaction and illumination damages of CS@ZnS:Mn D-dots with bovine serum albumin (BSA) were studied by means of ultraviolet–visible (UV–vis) and fluorescence (FL) spectra. It was found that the FL of BSA was quenched by CS@ZnS:Mn D-dots. The dominating quenching mechanism of CS@ZnS:Mn D-dots with BSA belongs to dynamic quenching. Hydrophobic interaction plays a major role in the CS@ZnS:Mn–BSA interaction; binding processes are spontaneous. Influencing factors such as illumination time and CS@ZnS:Mn D-dots concentrations were considered. The FL quenching effect of BSA by CS@ZnS:Mn D-dots is enhanced with the increase of illumination time and CS@ZnS:Mn D-dots concentration. The FL enhancement of CS@ZnS:Mn D-dots by BSA under UV illumination was also observed. It was proved that, the interaction of CS@ZnS:Mn D-dots with BSA under UV illumination is mainly a result of a photo-induced free radical procedure. CS@ZnS:Mn D-dots may be used as photosensitizers in photodynamic therapy.

Improvement of operation lifetime for conjugated polymer:fullerene organic solar cells by introducing a UV absorbing film

We have studied the lifetime improvement of organic solar cells based on conjugated polymer:fullerene blends using a UV absorbing film. The cell using P3HT and PCBM-71 exhibited a conversion efficiency of ∼4.3%, but it decreased with increase in illumination time. The conversion efficiency of the cells with and without UV film decreased to 6.6% and 37.6%, respectively, after 24 h of light exposure under AM1.5. The UV exposure appears to change the P3HT polymer network such that the defects are generated, resulting in the degradation of cell efficiency. It is found that the conversion efficiency of the cell having a 4 um UV blocking layer is higher than that without a UV layer after 12 h of illumination under 120 mW/cm 2.