Stability and decolourization ability of Trametes villosa laccase in liquid ultrasonic fields

We report in this study that the sonication of laccase from Trametes villosa and bovine serum albumin promotes the formation of protein aggregates with high molecular weight. The formation of aggregates leads to the deactivation of the enzyme, fact that was confirmed by the analysis of the enzyme stability (half-life time) upon ultrasound treatment. This inactivation was mainly caused by the radicals formed by the cavitation phenomenon. It was verified that the addition of polyvinyl alcohol to laccase had a protecting effect against enzyme inactivation. The performance of laccase in the decolourization of indigo carmine was studied. It was observed that the best results were attained when the dye solution was treated with ultrasound and enzyme stabilized with polyvinyl alcohol, where more than 65% of decolourization was achieved. This value is remarkably higher than that attained for the enzyme alone, which was only able to decolourize 20% of the dye solution within 1h of treatment. These results have important implications for the exploitation of sonication in textile industry, where the pollution caused by the release of dyes into effluents is one of the major concerns.     

Ecofriendly laccase–hydrogen peroxide/ultrasound-assisted bleaching of linen fabrics and its influence on dyeing efficiency

This study evaluates the bleaching efficiency of enzymatically scoured linen fabrics using a combined laccase–hydrogen peroxide bleaching process with and without ultrasonic energy, with the goal of obtaining fabrics with high whiteness levels, well preserved tensile strength and higher dye uptake. The effect of the laccase enzyme and the combined laccase–hydrogen peroxide bleaching process with and without ultrasound has been investigated with regard to whiteness value, tensile strength, dyeing efficiency and dyeing kinetics using both reactive and cationic dyes. The bleached linen fabrics were characterized using X-ray diffraction and by measuring tensile strength and lightness. The dyeing efficiency and kinetics were characterized by measuring dye uptake and colour fastness. The results indicated that ultrasound was an effective technique in the combined laccase–hydrogen peroxide bleaching process of linen fabrics. The whiteness values expressed as lightness of linen fabrics is enhanced by using ultrasonic energy. The measured colour strength values were found to be slightly better for combined laccase–hydrogen peroxide/ultrasound-assisted bleached fabrics than for combined laccase–hydrogen peroxide for both reactive and cationic dyes. The fastness properties of the fabrics dyed with reactive dye were better than those obtained when using cationic dye. The time/dye uptake isotherms were also enhanced when using combined laccase–hydrogen peroxide/ultrasound-assisted bleached fabric, which confirms the efficiency of ultrasound in the combined oxidative bleaching process. The dyeing rate constant, half-time of dyeing and dyeing efficiency have been calculated and discussed.     

Ultrasonic pilot-scale reactor for enzymatic bleaching of cotton fabrics

The potential of ultrasound-assisted technology has been demonstrated by several laboratory scale studies. However, their successful industrial scaling-up is still a challenge due to the limited pilot and commercial sonochemical reactors. In this work, a pilot reactor for laccase-hydrogen peroxide cotton bleaching assisted by ultrasound was scaled-up. For this purpose, an existing dyeing machine was transformed and adapted by including piezoelectric ultrasonic devices. Laboratory experiments demonstrated that both low frequency, high power (22 kHz, 2100 W) and high frequency, low power ultrasounds (850 kHz, 400 W) were required to achieve satisfactory results. Standard half (4 g/L H₂O₂ at 90 °C for 60 min) and optical (8 g/L H₂O₂ at 103 °C for 40 min) cotton bleaching processes were used as references. Two sequential stages were established for cotton bleaching: (1) laccase pretreatment assisted by high frequency ultrasound (850 kHz, 400 W) and (2) bleaching using high power ultrasound (22 kHz, 2100 W). When compared with conventional methods, combined laccase-hydrogen peroxide cotton bleaching with ultrasound energy improved the whitening effectiveness. Subsequently, less energy (temperature) and chemicals (hydrogen peroxide) were needed for cotton bleaching thus resulting in costs reduction. This technology allowed the combination of enzyme and hydrogen peroxide treatment in a continuous process. The developed pilot-scale reactor offers an enhancement of the cotton bleaching process with lower environmental impact as well as a better performance of further finishing operations.     

Sonochemical and hydrodynamic cavitation reactors for laccase/hydrogen peroxide cotton bleaching

The main goal of this work is to develop a novel and environmental-friendly technology for cotton bleaching with reduced processing costs. This work exploits a combined laccase–hydrogen peroxide process assisted by ultrasound. For this purpose, specific reactors were studied, namely ultrasonic power generator type K8 (850 kHz) and ultrasonic bath equipment Ultrasonic cleaner USC600TH (45 kHz). The optimal operating conditions for bleaching were chosen considering the highest levels of hydroxyl radical production and the lowest energy input. The capacity to produce hydroxyl radicals by hydrodynamic cavitation was also assessed in two homogenizers, EmulsiFlex®-C3 and APV-2000. Laccase nanoemulsions were produced by high pressure homogenization using BSA (bovine serum albumin) as emulsifier. The bleaching efficiency of these formulations was tested and the results showed higher whiteness values when compared to free laccase. The combination of laccase–hydrogen peroxide process with ultrasound energy produced higher whiteness levels than those obtained by conventional methods. The amount of hydrogen peroxide was reduced 50% as well as the energy consumption in terms of temperature (reduction of 40 °C) and operating time (reduction of 90 min).     

Establishing an ultrasound-assisted activated peroxide system for efficient and sustainable scouring-bleaching of cotton/spandex fabric

This study presents a high-efficient and cost-effective ultrasound-assisted strategy for one-bath one-step scouring and bleaching of cotton/spandex fabric using sodium percarbonate (SPC) and tetraacetylenediamine (TAED) couple. SPC plays both roles of pH regulator and H₂O₂ donor to initiate the peracetic acid (PAA) release from TAED. The significance and interaction effects of operating parameters (TAED concentration, temperature and time) on the WI (Whiteness Index) of fabrics were investigated through a central composite design. The bleaching mechanism was studied by exploring the relationship between WI and PAA and hydroxyl radical (HO·) concentrations. The mechanical and dyeing performances of treated fabrics were also evaluated. Results show that temperature exerted a significant impact on WI followed by TAED concentration and time. The PAA concentration decreased and HO· concentration increased upon the temperature rise. Both PAA and HO· were significant to upgrade WI and ultrasound was effective in enhancing their bleaching efficiency. The fabric treated only with 15 mmol/L TAED and 10 mmol/L SPC at 40 °C for 40 min under ultrasound could achieve a WI of 68.6 (43% higher than greige fabric), which was almost equivalent to that of the fabric treated at 60 °C without ultrasound. This verifies the contribution of ultrasound technology in reducing bleaching temperature for energy-saving purpose. Moreover, the treated fabric displayed less than 5% tensile strength loss, having a marginal impact on the apparel performance. The wettability of fabric was greatly improved leading to a good dyeing performance. Encouraging results demonstrate the high efficiency of the ultrasound-assisted pre-treatment process of cotton/spandex fabric, which contributes to the sustainable production of textiles.     

木素小分子愈创木基型松柏醇漆酶生物改性的光谱分析

从分子模型物的角度入手,通过气相色谱-质谱联用(GC-MS)、凝胶渗透色谱(GPC)、红外光谱和颗粒电荷等测试手段,综合考察了漆酶对针叶木和阔叶木中的愈创木基型木素-松柏醇生物改性的机理。松柏醇经漆酶处理后,GC-MS检测不到松柏醇单体的存在,推测松柏醇参与了化学反应,结构发生变化。GPC分析证明松柏醇漆酶处理后分子量变大,松柏醇发生了聚合。红外光谱确定了松柏醇漆酶处理过程中反应位点,主要是酚羟基、苯环上的甲氧基、苯环侧链上的双键,β碳、γ碳也有可能参与了反应。颗粒电荷测定仪(PCD)测得阳离子需求量下降了88.38%。     

Individual and combined effects of ultrasound, ozone and UV irradiation: a case study with textile dyes

Comparative degradation of azo dyes by 520 kHz ultrasonic irradiation and its combinations with ozone and/or ultraviolet light (UV) was investigated using a probe dye C.I. Acid Orange 7. Operation parameters such as ultrasonic power density, ozone flow, UV intensity, and type and injection mode of the bubbling gas were optimized based on the rate of absorption decay in the visible and UV bands as estimated by regression analysis of absorption-time data. At equivalent initial dye concentrations and contact times, individual effects of UV irradiation, ultrasound and ozone were "no effect", "bleaching", and "bleaching/organic carbon degradation", respectively. UV irradiation, however, was found to induce a catalytic effect when applied in combination with either ultrasound or ozone schemes; and the overall degradation process was most rapid under simultaneous operation of the three in the presence of a continuous flow of a gas mixture made of argon and oxygen. The synergy observed in combined schemes was attributed to enhanced ozone diffusion by mechanical effects of ultrasound, and the photolysis of ultrasound-generated H(2)O(2) to produce hydroxyl radicals.     

Use of ultrasonic energy for intensification of the bio-preparation of greige cotton

Raw unscoured cotton contains approximately 90% cellulose and various noncellulosic impurities such as waxes, pectins, proteins, and fats. To remove these hydrophobic noncellulosics and produce a highly absorbent fiber that can be dyed and finished uniformly, the greige cotton is traditionally processed with relatively harsh and environmentally unfriendly chemicals. New bio-preparation processes that utilize highly specific enzymes instead of conventional organic/inorganic chemicals are becoming increasingly popular in the textile industry. The major shortcoming of this new technology is that the processing time is much longer than the conventional method. This limitation was overcome by use of ultrasound energy in combination with enzyme processing. The combined enzyme/ultrasound bio-preparation of greige cotton offers significant advantages such as less consumption of expensive enzymes, shorter processing time, better uniformity of treatment and a notable decrease in the amount and toxicity of the resulting textile wastewater effluents.     

Time-dependent micro-Raman scattering studies of polyvinyl alcohol and silver nitrate thin films

In-situ monitoring of silver nanoparticle formation was studied in thin films of polyvinyl alcohol and silver nitrate. We proposed the observation of surface-enhanced Raman spectroscopy (SERS) as a novel and simple technique to record the growth of silver nanoparticles in polyvinyl alcohol thin films. Observed enhancement in the Raman bands of polyvinyl alcohol is explained through the localized surface plasmon resonance of silver nanoparticles. Influence of temperature generated by silver nanoparticles on the formation of nanoparticles is also discussed.     

Er-doped all-fiber laser mode-locked by graphitic carbon nitride nanosheets

Few-layer graphitic carbon nitride(g-C_3N_4) nanosheets were fabricated and utilized as a saturable absorber for mode-locking in an Er-doped fiber laser with net normal dispersion. The g-C_3N_4/polyvinyl alcohol(PVA) hybrid-film-based saturable absorber has a modulation depth of 4.01% and a saturation intensity of 7.5 MW/cm~2. By integrating g-C_3N_4-PVA mode-locker into the laser cavity, a mode-locked operation could be obtained. The achieved mode-locking pulse centered at 1530.3 nm has a pulse width of 530 ps. Its repetition rate is 40.8 MHz, and the corresponding signal-to-noise ratio is about 55 dB.     

铽配合物荧光及在农用光波长转换塑料薄膜中的应用

选择荧光效应强的稀土元素铽,以磺基水杨酸作为第一配体,以聚乙烯醇、聚乙二醇2000等为协配体,对乙醇溶液和水溶液两个体系中形成的配合物荧光进行了研究。试验确定了铽、磺基水杨酸以及聚乙烯醇、聚乙二醇2000为优良协配体的最佳用量。进一步研究发现,表面活性剂的加入对不同配合物的荧光均会产生增强效果,十二烷基磺酸钠效果最好;同时探索了酸度对体系荧光强度的影响。对于获得的铽-磺基水杨酸-聚乙烯醇配合物,其荧光激发波长为342 nm,而荧光发射波长为545 nm,将该配合物以适当比例掺加到农用塑料薄膜中,制备出可以使太阳光的紫外部分转换为作物光合作用需要的绿光的稀土光转换膜。     

红外光谱分析木质素在漆酶酶法改性中的反应性

随着非水酶学的发展,木质素的酶法催化改性得到日益广泛的运用。文章主要考察了漆酶酶法改性反相微乳液体系中云杉碱木质素、乙醇水溶液中乙醇木质素、缓冲液体系中木质素磺酸盐、以及碱溶液中汽爆麦草碱木质素的反应。通过红外光谱对各反应体系中,漆酶催化改性后的木质素结构特点进行分析,结合凝胶色谱法考察木质素的分子量及其分布,结果表明经过YY-5漆酶处理后各种木质素的分子量分布均趋向于高分子区域,且分子量分散性降低,各种木质素的红外光谱结构也发生了明显的变化。初步确定了木质素在漆酶催化改性中存在的反应位点,主要是酚羟基、苯环侧链取代基、羰基等。在四种木质素中,漆酶对碱木质素的改性反应性要高于其他类型的木质素,这可能与碱性溶液体系中漆酶的活性较高有关。     

Photobleaching with a subnanosecond laser flash

In standard fluorescence recovery after photobleaching (FRAP) applications for measuring lateral diffusion rates and adsorption/desorption kinetics of fluorescent molecules at biological or model membranes, irreversible bleaching is induced by a bright excitation flash of at least millisecond time scale. It has been presumed that the bleaching event is of a low probability and the significant bleached population that develops during the flash results from each molecule undergoing thousands of excitation/deexcitation cycles before a bleaching event occurs. In some FRAP experiments, notably polarized FRAP (PFRAP) for measuring molecular rotational diffusion rates, it is desirable to use much shorter (subnanosecond) bleaching pulses. However, subnanosecond pulses are shorter than the fluorescence lifetime, so that any fluorophore will experience at most only one visit to the excited state during the bleaching pulse. If bleaching occurs only by the same processes as in slower FRAP experiments, one would thereby expect only minimal bleaching regardless of the bleach intensity. Moreover, the ability of fast polarized pulses to imprint an anisotropic orientational pattern in the postbleach unbleached fluorophore, an ability essential for PFRAP, is not at all guaranteed, particularly if two-photon processes are involved in high-intensity short bleach pulses. In this study, bleaching depths are measured as a function of subnanosecond pulse intensity on a small labeled protein covalently immobilized on fused silica. We show that bright subnanosecond laser flashes do indeed produce significant bleaching, that both two photon effects and reversible bleaching are involved, and that polarized bleaching does produce an anisotropic orientational pattern of unbleached fluorophore. We also postulate a theoretical molecular state model which semiquantitatively accounts for the experimentally observed dependence of reversible bleaching on bleaching pulse intensity.     

Ultrasound promoted reaction of Rhodamine B with sodium hypochlorite using sonochemical and dental ultrasonic instruments

The sonochemical acceleration of bleaching of Rhodamine B by sodium hypochlorite has been studied using ultrasound intensities in the range 0-7 W cm(-2). Using a 20 kHz ultrasonic horn, it was shown that ultrasound could significantly shorten the treatment time and/or the concentration of hypochlorite required for the reaction. A number of intermediate species formed during the reaction have been identified. It was demonstrated that the same sonochemical reactions occur during the use of dental ultrasound instruments of the type used in endodontics where hypochlorite solutions act as disinfectants. Results showed pseudo-first order degradation kinetics for the degradation of Rhodamine B for both types of source. Both the distribution of cavitation and the resulting bleaching reactions were dependent on the design of the tips. The bleaching reaction can therefore be used to characterise the behaviour of dental instruments and aid in the optimisation of their performance.     

Influence of argon/oxygen atmospheric dielectric barrier discharge treatment on desizing and scouring of poly (vinyl alcohol) on cotton fabrics

The effect of argon/oxygen atmospheric dielectric barrier discharge (DBD) treatment on desizing and scouring of polyvinyl alcohol (PVA) on cotton fabric was studied with respect to the treatment duration of 1, 2, 4 and 6 min. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen concentration increased for the plasma treated PVA film. Solubility measurement revealed that plasma treatment increased PVA solubility in hot washing but less effective in cold washing. Scanning electron microscopy (SEM) showed that the fiber surfaces were as clean as unsized fibers after 6 min treatment followed by hot washing. Wickability analysis indicated that the capillary heights of plasma treated fabrics increased significantly as the plasma treatment duration increased. The results of the yarn tensile strength test showed that the plasma treatment did not have a negative effect on fabric tensile strength.     

Optimization of a holographic memory setup using an LCD and a PVA-based photopolymer

Holographic data pages were stored in a polyvinyl alcohol (PVA)/acrylamide (AA) photopolymer. This material is formed of AA photopolymers which are considered interesting materials for recording holographic memories. A liquid crystal device was used to modify the object beam and store the data pages in the material. During the storage process, some parameters like exposure time, beam ratio and reading beam intensity were controlled to obtain high image quality after the reconstruction process. The bit error rate (BER) was calculated fitting the histograms of the images to determine what parameters improve the quality of the images.     

Preparation and characterization of polyvinyl alcohol—chitosan biocompatible magnetic microparticles

This work addresses the obtaining of biocompatible magnetic polyvinyl alcohol—chitosan microspheres, specifically tailored/functionalised to bind directly blood toxins using an emulsion crosslinking preparation method. The following synthesis parameters were studied: water to oil phase ratio, polyvinyl alcohol molecular weight, chitosan to polyvinyl alcohol weight ratio, surfactant composition and concentration of the crosslinking agent. These parameters were optimized for producing a high yield of colloidally stable and uniformly sized particles with significant magnetization of saturation, bearing surface amino groups that can be further used to bind blood toxins directly. The particles were characterized regarding their size distribution and surface charge (laser diffraction analysis), morphology (transmission electron microscopy), magnetic properties, chemical composition (Fourier transform infrared spectroscopy) and concentration of the surface amino groups (conductometric titration).     

Bleaching and diffusion of laser dyes in solution under high power UV irradiation

Bleaching experiments in some laser dyes under high power UV irradiation from a nitrogen laser are described. Very high bleaching quantum efficiencies, of the order of 10^-3 molecules bleached/photon absorbed, and a dependence of this efficiency on intensity have been found. The diffusion coefficients for the dyes in ethyl alcohol were also measured.     

Fluorescence of N,N′-dimethylaminobenzonitrile in polyvinyl alcohol stretched films

We have demonstrated that the conditions of the charge-transfer (CT) reaction in the N,N′-dimethylaminobenzonitrile (DMABN) molecule in polyvinyl alcohol (PVA) polymer matrices can be considerably changed upon their stretching deformation. The fluorescence spectrum of DMABN in PVA has two characteristic bands in the ultraviolet (UV) and visible spectral ranges, which indicates that a CT reaction proceeds in the excited state. Stretching leads to a strong decrease in the intensity of the UV band, the contribution of which in undeformed samples is comparable with the emission in the violet range. Even single stretching PVA films strongly reduces the emission intensity of the UV band, with this effect being dramatically enhanced upon sixfold stretching. In the latter case, The fluorescence spectrum is characterized by a strong CT band, the relative intensity of which is 3.5 times higher than even in a strongly polar aprotic solvent, such as acetonitrile. The obtained data indicate that, as a result of mechanical stretching, it becomes possible to change basic intermolecular factors that affect the CT rate in PVA samples.     

Organic dye-doped polymer films for optical phase-conjugate processing

Erythrosin B-doped polyvinyl alcohol (EB/PVA) film, a methyl-orange-doped polyvinyl alcohol (MO/PVA) film and a (EB+MO)/PVA film serve as not only phase conjugators but also hologram-recording media. A phase-conjugate (PC) wave is generated even when a probe wave is linear-polarized orthogonal to the pump polarization direction. Using these dye-doped films, we demonstrate optical PC processing for detecting the phase and amplitude difference between two objects and a moving or time-varying object in a backward degenerate four-wave mixing arrangement.