Off-line two-dimensional liquid chromatography for metabolomics: an example using Agaricus bisporus mushrooms exposed to UV irradiation

It has previously been shown that irradiation with UV light increases the vitamin D content of certain mushroom species, but the effect on other nutrients is unknown, and is difficult to assess due to the complexity of the sample matrix. Here, an offline reversed phase × reversed phase two-dimensional liquid chromatography methodology was developed and applied to Agaricus bisporus mushrooms in order to demonstrate the potential of the technique and assess the effect of UV irradiation on the mushroom’s metabolic profile. The method allowed the detection of 158 peaks in a single analytical run. A total of 51 compounds including sugars, amino acids, organic and fatty acids and phenolic compounds were identified using certified reference standards. After irradiation of the mushrooms with UV for 30 s the number of peaks detected decreased from 158 to 150; 47 compounds increased in concentration while 72 substances decreased. This is the first time that two-dimensional liquid chromatography has been carried out for the metabolomic analysis of mushrooms. The data provide an overview of the gain/loss of nutritional value of the mushrooms following UV irradiation and demonstrate that the increased peak capacity and separation space of two-dimensional liquid chromatography has great potential in metabolomics.

Photocatalytic degradation of dyes in wastewater using TiO2/UV in a flat-plate reactor

The photocatalyst TiO₂ with UV irradiation was used to degrade dyes in textile effluent in a flat-plate photoreactor. A test system was built with the reactor area of 1 x 0.3m2, UV light of six 36W-blacklight. TiO₂ powder P25 with BET surface area 50±15m2/g, average primary particle size 21 nm, purity> 99.5% and content of 83.9% anatase and 16.1 % rutile was used as the photocatalyst. A number of dyes commonly present in dyeing wastewater were tested in this study. The different operating parameters, such as dosage of photocatalyst, the structure of the reactor, flow rates through the flat-plate reactor, UV radiation intensity and tilted angle of the reactor, were investigated. The results showed that the photocatalytic process could efficiently remove most of the colour contained in the dyeing wastewater. It was experimentally observed that first-order kinetics was adequate for characterising the process. The flow rate and the tilted angle had some influence on the film thickness of the fluid in the reactor and the empirical correlation between the film thickness of the fluid and these two parameters was developed. The photoreaction rate was mainly determined by the film thickness of the fluid on the reactor surface and the dosage of the photocatalyst. Optimum operating parameters of the system were found to be at the film thickness of about 1.4mm and a TiO₂ dosage of 1 gIL. The higher the UV intensity, the faster the reaction rate was. The results of these experiments showed that this method has the great potential for colour removal from wastewater at commercial scale.

To overcome the common difficulty of separating the used TiO₂ suspension after treatment precipitation followed with filtration was used in this study to determine the separation efficiencies. On the other hand, TiO₂ in a small pillar shape was also studied for photocatalytic degradation of textile dye effluent. The pillar pellet was made in Oegussa Company, Germany ranging from 2.5 to 5.3mm long and with a diameter of 3.7mm. It was almost pure TiO₂ (83.2% anatase and 16.8% rutile), with a S-content of <20 ppm and a CI content of the order of 0.1 wt. %. No further elements are present in contents above 0.05 wt.%. The TiO₂ pillars were placed on the flat-plate reactor that was divided by the rectangular slots and irradiated under UV light when the treated solution went through the reactor. Four dyes and their mixtures were tested. The results showed that the photocatalytic process under this configuration efficiently remove the colour from textile dyeing effluent, and pillar shape TiO₂ photocatalyst was not dissolved in water and very easy to be separated from solution, enabling it to be reused many times. The first-order kinetics was adequate for characterising the photocatalytic degradation process and the photocatalytic performance was comparable to TiO₂ powder. It is believed that the TiO₂ pellet would be a preferable form of photocatalyst in applications for textile effluent treatment process, and other wastewater treatment processes.

UV-induced DNA damage promotes resistance to the biotrophic pathogen Hyaloperonospora parasitica in Arabidopsis

Plant innate immunity to pathogenic microorganisms is activated in response to recognition of extracellular or intracellular pathogen molecules by transmembrane receptors or resistance proteins, respectively. The defense signaling pathways share components with those involved in plant responses to UV radiation, which can induce expression of plant genes important for pathogen resistance. Such intriguing links suggest that UV treatment might activate resistance to pathogens in normally susceptible host plants. Here, we demonstrate that pre-inoculative UV (254 nm) irradiation of Arabidopsis (Arabidopsis thaliana) susceptible to infection by the biotrophic oomycete Hyaloperonospora parasitica, the causative agent of downy mildew, induces dose- and time-dependent resistance to the pathogen detectable up to 7 d after UV exposure. Limiting repair of UV photoproducts by postirradiation incubation in the dark, or mutational inactivation of cyclobutane pyrimidine dimer photolyase, (6-4) photoproduct photolyase, or nucleotide excision repair increased the magnitude of UV-induced pathogen resistance. In the absence of treatment with 254-nm UV, plant nucleotide excision repair mutants also defective for cyclobutane pyrimidine dimer or (6-4) photoproduct photolyase displayed resistance to H. parasitica, partially attributable to short wavelength UV-B (280–320 nm) radiation emitted by incubator lights. These results indicate UV irradiation can initiate the development of resistance to H. parasitica in plants normally susceptible to the pathogen and point to a key role for UV-induced DNA damage. They also suggest UV treatment can circumvent the requirement for recognition of H. parasitica molecules by Arabidopsis proteins to activate an immune response.

Nano titanium dioxide on wool keratin as UV absorber stabilized by butane tetra carboxylic acid (BTCA): a statistical prospect

Photo yellowing of wool is one of the most important problems which have negative impacts on various aspects of wool prompting scientists to find a solution over the past decades. In this research the protective features of nano-titanium dioxide particles against UV on wool fabric were discussed and the color variations of wool samples after UV irradiation were measured and reported. It was shown that nano TiO2 is a suitable UV absorber and its effect depends on the concentration. Also, it was assumed that butane tetracarboxylic acid plays a prominent role as a cross-linking agent to stabilize the nano-titanium dioxide as well as a polyanion to maintain negative charges on the wool surface for higher nano particles absorption. Also the variables conditions were optimized using response surface methodology (RSM).

Photocatalytic reduction of carbon dioxide

Carbon dioxide reforming happens all the time in nature by photosynthesis of plants. It thus provides a great challenge to equal or surpass this photosynthesis in an artificial system. This paper presents a literature review of using semi-conductor to assist photocatalytic reduction of carbon dioxide under UV irradiation. It analyses some key factors influencing the reaction rates which have been studied worldwide in respective areas. Special interest is taken in recommending possible improvements for the heterogeneous photocatalysis involving gas-solid interfaces, particularly in relation to the influencing factors affecting product concentrations and the reduction rate.

Photocatalytic reduction of carbon dioxide into gaseous hydrocarbon using TiO2 pellets

It has been shown that CO₂ could be transformed into hydrocarbons when it is in contact with water vapour and catalysts under UV irradiation. This paper presents an experimental set-up to study the process employing a new approach of heterogeneous photocatalysis using pellet form of catalyst instead of immobilized catalysts on solid substrates. In the experiment, CO₂ mixed with water vapour in saturation state was discharged into a quartz reactor containing porous TiO₂ pellets and illuminated by various UV lamps of different wavelengths for 48 h continuously. The gaseous products extracted were identified using gas chromatography. The results confirmed that CO₂ could be reformed in the presence of water vapour and TiO₂ pellets into CH₄ under continuous UV irradiation at room conditions. It showed that when UVC (253.7 nm) light was used, total yield of methane was approximately 200 ppm which was a fairly good reduction yield as compared to those obtained from the processes using immobilized catalysts through thin-film technique and anchoring method. CO and H₂ were also detected. Switching from UVC to UVA (365 nm) resulted in significant decrease in the product yields. The pellet form of catalyst has been found to be attractive for use in further research on photocatalytic reduction of CO₂.

Enhanced degradation efficiency of toluene using titania/silica photocatalysis as a regeneration process

Three kinds of titania/silica pellets were prepared using the sol-gel method with surface areas of 50.4m² g-1, 421.1m².g^-1 and 89.1m².g^-1. An annular reactor was designed and built to determine the degradation efficiency of toluene and to investigate the relationship between the adsorption and desorption-photocatalytic processes. Surface area is an important factor influencing the adsorption-photocatalytic efficiency. Higher surface areas of pellets contribute to high rates of conversion of toluene. Un-reacted toluene and reaction intermediates accumulating on their surface deactivated the titania/silica catalyst. To overcome this problem, the adsorption and regeneration process were alternated in a dual reactor system. Connecting or disconnecting the toluene feed gas enabled one reactor to adsorb toluene, while the second reactor was regenerated by photocatalysis. Using UV irradiation and titania/silica pellets with high BET surface area (421.1 m².g^-1), the alternating adsorption/regeneration processes kept the degradation efficiency of toluene at 90% after 8 hours operation. By improving the adsorption-photocatalysis efficiency, and minimising the generation and accumulation of intermediate on the surface of pellets, the method extended catalyst life and maintained a high degradation efficiency of toluene.

Using titania photocatalysts to degrade toluene in a combined adsorption and photocatalysis process

Three types of titania supported materials including titanium dioxide and silicon dioxide composite, titania-coated activated carbon and titania-coated glass beads were prepared and used as photocatalysts to remove toluene from an air stream. Their surface areas were analysed. TEM image reveals titania-silica composites were nanostructured aggregates. XRD was used to determine their crystalline phase which was 100% anatase for the titania component. A fixed bed reactor was designed and built in the laboratory, the toluene with initial concentration of 300 ppm (1149 mg/m³) was fed into the reactor, the destruction efficiencies of toluene were determined by the gas analyser. It was also found that TiO₂-SiO₂ aggregates with high surface area (421.1 m²/g) achieved high destruction efficiencies. The combined effects of adsorption and photocatalysis were further studied by comparing the performance of pure activated carbon (surface area of 932.4 m²/g) and TiO₂ coated activated carbon with BET surface area of 848.4 m²/g. It was found that the TiO₂ coated activated carbon demonstrated comparable results to pure activated carbon, and most importantly, the TiO₂-coated activated carbon can be effectively regenerated by UV irradiation, and was reused as adsorbent. The experimental result of titania-coated glass beads demonstrated a steady degradation efficiency of 15% after a period of 17 hours. It helped to understand that photocatalysis degradation ability of the TiO₂ was constant regardless of the adsorption capacity of the catalysts. This photocatalytic property can be used to degrade the adsorbed toluene and regenerate the catalyst. This study revealed that if the experiments were designed to use adsorption to remove toluene and followed by regeneration of adsorbent using photocatalysis, it could achieve a very high removal efficiency of toluene and reduce the regeneration cost of saturated adsorbent.

Removal of VOCs by photocatalysis process using adsorption enhanced TiO2–SiO2 catalyst

Volatile organic compounds (VOCs) exist widely in both the indoor and outdoor environment. The main contributing sources of VOCs are motor vehicle exhaust and solvent utilization. Some VOCs are toxic and carcinogenic to human health, such as benzene. In this study, TiO₂–SiO₂ based photocatalysts were synthesized using the sol–gel method, with high surface areas of 274.1–421.1 m²/g obtained. Two types of pellets were used as catalysts in a fixed-bed reactor installed with a UV black light lamp. Experiments were conducted to compare their efficiencies in degrading the VOCs. Toluene was used as the VOC indicator. When the toluene laden gas stream passed through the photocatalytic reactor, the removal efficiencies were determined using a FTIR multi-gas analyser, which was connected to the outlet of the reactor to analyse the toluene concentrations. As the TiO₂–SiO₂ pellets used have a high adsorption capacity, they had dual functions as a photocatalyst and adsorbent in the hybrid photocatalysis and adsorption system. The experiments demonstrated that the porous photocatalyst with very high adsorptive capacity enhanced the subsequent photocatalysis reactions and lead to a positive synergistic effect. The catalyst can be self-regenerated by photocatalytic oxidation of the adsorbed VOCs. When the UV irradiation and feeding gas is continuous, a destruction efficiency of about 25% was achieved over a period of 20 h. Once the system was designed and operated into adsorption/regeneration mode, a higher removal efficiency of about 55% was maintained. It was found that the catalyst pellets with a higher surface area (421 m²/g) achieved higher conversion efficiency (100%) for a longer period than those with a lower surface area. A full spectrum scan was carried out using a Bio-rad Infrared spectrometer, finding that the main components of the treated gas stream leaving the reactor, along with untreated toluene, were CO₂ and water. The suspected intermediates of aliphatic hydrocarbons and CO were found in minimal amounts or were non detectable. The kinetic rate constants were calculated from the experimental results, it appeared that the stronger adsorption capacity, i.e. larger specific surface area, the higher conversion efficiency would be achieved.

A morphology-related study on photodegradation of protein fibres

The wool fibre has a complex morphology, consisting of an outer layer of cuticle scales surrounding an inner cortex. These two components are hard to separate effectively except by using harsh chemical treatments, making it difficult to determine the susceptibility of the different components of the fibre to photoyellowing. An approach to this problem based on mechanical fibre modification is described. To expose the inner cortex of wool to different degrees, clean wool fibres were converted into ‘powders’ of various fineness via mechanical chopping, air-jet milling, ball milling or their combination. Four types of powdered wool (samples A, B, C and D) were produced with reducing particle size distributions and an increasing level of surface damage as observed using SEM. Sample A contained essentially intact short fibre snippets and sample D contained a large amount of exposed cortical materials. Samples B and C contained a mixture of short fibre snippets and cortical materials. Solid wool discs were then compressed from the corresponding powder samples in a polished stainless steel die to enable colour measurement and UV irradiation studies. ATR-FTIR studies on powder discs demonstrated a small shift in the amide I band from 1644 cm−1 for disc A to 1654 cm−1 for disc D due to the different structures of the wool cuticle and cortex, in agreement with previous studies. Similarly an increase in the intensity ratio of the amide I to amide II band (1540 cm−1) was observed for disc D, which contains a higher fraction of cortical material at the surface of the disc.

Discs prepared from sample D appeared the lightest in colour before exposure and had the slowest photoyellowing rate, whereas discs made from powders A–C with a higher level of cuticle coverage were more yellow before exposure and experienced a faster rate of photoyellowing. This suggests that the yellow chromophores of wool may be more prevalent in cuticle scales, and that wool photoyellowing occurs to a greater extent in the cuticle than in the cortex. Photo-induced chemiluminescence measurements showed that sample D had a higher chemiluminescence intensity after exposure to UVA radiation and a faster decay rate than samples A and B. Thus one of the roles of the wool cuticle may be to protect the cortex by quenching of free radical oxidation during exposure to the UV wavelengths present in sunlight.

Photochromic wool fabric by sol-gel coating and photochromism

The application of photochromism in textiles has potential to create new opportunities to develop fancy colour-changing effects in fashionable textiles, as well as smart garments capable of protecting wearers from the effects of UV irradiation and responding to environmental changes. This book presents a coating method for achieving quick and obvious photochromic effects on wool fabrics using conventional photochromic dyes and hybrid silicas. It covers details about fabricating different types of photochromic dye-silica coatings, measuring their optical performance, assessing some physical characterisations of the coatings, and measuring the effects of the coatings on fabric performance.

Photoreactive azido-containing silica nanoparticle/polycation multilayers : durable superhydrophobic coating on cotton fabrics

In this study, we report the functionalization of silica nanoparticles with highly photoreactive phenyl azido groups and their utility as a negatively charged building block for layer-by-layer (LbL) electrostatic assembly to produce a stable silica nanoparticle coating. Azido-terminated silica nanoparticles were prepared by the functionalization of bare silica nanoparticles with 3-aminopropyltrimethoxysilane followed by the reaction with 4-azidobenzoic acid. The azido functionalization was confirmed by FTIR and XPS. Poly(allylamine hydrochloride) was also grafted with phenyl azido groups and used as photoreactive polycations for LbL assembly. For the photoreactive silica nanoparticle/polycation multilayers, UV irradiation can induce the covalent cross-linking within the multilayers as well as the anchoring of the multilayer film onto the organic substrate, through azido photochemical reactions including C–H insertion/abstraction reactions with surrounding molecules and dimerization of azido groups. Our results show that the stability of the silica nanoparticle/polycation multilayer film was greatly improved after UV irradiation. Combined with a fluoroalkylsilane post-treatment, the photoreactive LbL multilayers were used as a coating for superhydrophobic modification of cotton fabrics. Herein the LbL assembly method enables us to tailor the number of the coated silica nanoparticles through the assembly cycles. The superhydrophobicity of cotton fabrics was durable against acids, bases, and organic solvents, as well as repeated machine wash. Because of the unique azido photochemistry, the approach used here to anchor silica nanoparticles is applicable to almost any organic substrate.

Reversible photorheological lyotropic liquid crystals

We describe novel lyotropic liquid-crystalline (LLC) materials based on photoresponsive amphiphiles that exhibit rapid photoswitchable rheological properties of unprecedented magnitude between solidlike and liquidlike states. This was achieved through the synthesis of a novel azobenzene-containing surfactant (azo-surfactant) that actuates the transition between different LLC forms depending on illumination conditions. Initially, the azo-surfactant/water mixtures formed highly ordered and viscous LLC phases at 20-55 wt % water content. Spectroscopic, microscopic, and rheological analysis confirmed that UV irradiation induced the trans to cis isomerization of the azo-surfactant, leading to the disruption of the ordered LLC phases and a dramatic, rapid decrease in the viscosity and modulus resulting in a 3 orders of magnitude change from a solid (20,000 Pa) to a liquid (50 Pa) at rate of 13,500 Pa/s. Subsequent exposure to visible light reverses the transition, returning the viscosity essentially to its initial state. Such large, rapid, and reversible changes in rheological properties within this LLC system may open a door to new applications for photorheological fluids.

Selective, spontaneous one-way oil-transport fabrics and their novel use for gauging liquid surface tension

Thin porous materials that can spontaneously transport oil fluids just in a single direction have great potential for making energy-saving functional membranes. However, there is little data for the preparation and functionalities of this smart material. Here, we report a novel method to prepare one-way oil-transport fabrics and their application in detecting liquid surface tension. This functional fabric was prepared by a two-step coating process to apply flowerlike ZnO nanorods, fluorinated decyl polyhedral oligomeric silsesquioxanes, and hydrolyzed fluorinated alkylsilane on a fabric substrate. Upon one-sided UV irradiation, the coated fabric shows a one-way transport feature that allows oil fluid transport automatically from the unirradiated side to the UV-irradiated surface, but it stops fluid transport in the opposite direction. The fabric still maintains high superhydrophobicity after UV treatment. The one-way fluid transport takes place only for the oil fluids with a specific surface tension value, and the fluid selectivity is dependent on the UV treatment time. Changing the UV irradiation time from 6 to 30 h broadened the one-way transport for fluids with surface tension from around 22.3 mN/m to a range of 22.3-56.7 mN/m. We further proved that this selective one-way oil transport can be used to estimate the surface tension of a liquid simply by observing its transport feature on a series of fabrics with different one-way oil-transport selectivities. To our knowledge, this is the first example to use one-way fluid-transport materials for testing the liquid surface tension. It may open up further theoretical studies and the development of novel fluid sensors.

Photo induced silver on nano titanium dioxide as an enhanced antimicrobial agent for wool

In this study an effective nanocomposite antimicrobial agent for wool fabric was introduced. The silver loaded nano TiO(2) as a nanocomposite was prepared through UV irradiation in an ultrasonic bath. The nanocomposite was stabilized on the wool fabric surface by using citric acid as a friendly cross-linking agent. The treated wool fabrics indicated an antimicrobial activity against both Staphylococcus aureus and Escherichia coli bacteria. Increasing the concentration of Ag/TiO(2) nanocomposite led to an improvement in antibacterial activities of the treated fabrics. Also increasing the amount of citric acid improved the adsorption of Ag/TiO(2) on the wool fabric surface leading to enhance antibacterial activity. The EDS spectrum, SEM images, and XRD patterns was studied to confirm the presence of existence of nanocomposite on the fabric surface. The role of both cross-linking agent and nanocomposite concentrations on the results was investigated using response surface methodology (RSM).