Wavelength Ultraviolet Light Research Articles

Matrix-Assisted Photochemical Vapor Generation for the Direct Determination of Mercury in Domestic Wastewater by Atomic Fluorescence Spectrometry

ABSTRACT In this article, matrix-assisted photochemical vapor generation is proposed for the direct determination of mercury in domestic wastewater by atomic fluorescence spectrometry. With the ultraviolet light irradiation, the matrix (low-molecular-weight organic compounds) in domestic wastewater samples can produce reducing species. These reducing species could reduce mercury from mercury (II) to elemental mercury, subsequently swept by argon to atomic fluorescence spectrometry for detection. The effects of several factors, such as material of the photoreaction coil, ultraviolet light wavelength, ultraviolet light irradiation time, and flow rate of carrier gas, were investigated. Under the optimized condition, a limit of detection of 0.1 µg L−1 was obtained. The standard addition method was used for the spiked mercury domestic wastewater sample analysis, with a relative standard deviation (n = 11, at 20 µg L−1) of 4.8%, and recovery test results ranged from 81% to 110%. The proposed method was applied to analyze two certified reference materials and four domestic wastewater samples, with analytical results in good agreement with certified values or those obtained by ICP-MS. Interferences from common transition metals and alkaline metals as well as alkaline earth metals were also investigated. This is a simple, reagent-free, cost-effective, green method for mercury determination in domestic wastewater.

Novel fluorescent protein from Hydnophora rigida possesses green emission

Fluorescent proteins are a family of proteins capable of producing fluorescence at various specific wavelengths of ultra violet light. We have previously reported the identification and characterization of a novel cyan fluorescent protein (HriCFP) from a reef coral species, Hydnophora rigida. In search of new members of the diverse family of fluorescent proteins, here we report a new green fluorescent protein (HriGFP) from H. rigida. HriGFP was identified, cloned, expressed in Escherichia coli and purified to homogeneity by metal affinity and size exclusion chromatography. The dynamic light scattering and gel filtration experiments suggested the presence of monomers in solution. The peptide mass fingerprint on the purified protein established the identity of HriGFP. HriGFP had excitation peak at 507nm and emission peak at 527nm. HriGFP was similar to HriCFP except the last 16 amino acid sequence at the C-terminal; however, they have shown least similarity with other known fluorescent proteins. Moreover the computational model suggests that HriGFP is a globular protein which consists of 6 α-helices and 3 β-sheets. Taken together our results suggested that HriGFP is a novel naturally occurring fluorescent protein that exists as a monomer in solution.

ROS-mediated activation of Drosophila larval nociceptor neurons by UVC irradiation

BackgroundThe complex Drosophila larval peripheral nervous system, capable of monitoring sensory input from the external environment, includes a family of multiple dendritic (md) neurons with extensive dendritic arbors tiling the inner surface of the larval body wall. The class IV multiple dendritic (mdIV) neurons are the most complex with dendritic nerve endings forming direct intimate contacts with epithelial cells of the larval body wall. Functioning as polymodal mechanonociceptors with the ability to respond to both noxious mechanical stimulation and noxious heat, the mdIV neurons are also activated by nanomolar levels of the endogenous reactive oxygen species (ROS), H2O2. Although often associated with tissue damage related to oxidative stress, endogenous ROS have also been shown to function as signaling molecules at lower concentrations. The overall role of ROS in sensory signaling is poorly understood but the acutely sensitive response of mdIV neurons to ROS-mediated activation is consistent with a routine role in the regulation of mdIV neuronal activity. Larvae respond to short wavelength ultraviolet (UVC) light with an immediate and visual system-independent writhing and twisting of the body previously described as a nociceptive response. Molecular and cellular mechanisms mediating this response and potential relationships with ROS generation are not well understood. We have used the UVC-induced writhing response as a model for investigation of the proposed link between endogenous ROS production and mdIV neuron function in the larval body wall.ResultsTransgenic inactivation of mdIV neurons caused a strong suppression of UVC-induced writhing behavior consistent with a key role for the mdIV neurons as mediators of the behavioral response. Direct imaging of ROS-activated fluorescence showed that UVC irradiation caused a significant increase in endogenous ROS levels in the larval body wall and transgenic overexpression of antioxidant enzymes strongly suppressed the UVC-induced writhing response. Direct electrophysiological recordings demonstrated that UVC irradiation also increased neuronal activity of the mdIV neurons.ConclusionsResults obtained using UVC irradiation to induce ROS generation provide evidence that UVC-induced writhing behavior is mediated by endogenous production of ROS capable of activating mdIV mechanonociceptors in the larval body wall.

Ultraviolet vision in birds: the importance of transparent eye media

Ultraviolet (UV)-sensitive visual pigments are widespread in the animal kingdom but many animals, for example primates, block UV light from reaching their retina by pigmented lenses. Birds have UV-sensitive (UVS) visual pigments with sensitivity maxima around 360–373 nm (UVS) or 402–426 nm (violet-sensitive, VS). We describe how these pigments are matched by the ocular media transmittance in 38 bird species. Birds with UVS pigments have ocular media that transmit more UV light (wavelength of 50% transmittance, λT0.5, 323 nm) than birds with VS pigments (λT0.5, 358 nm). Yet, visual models predict that colour discrimination in bright light is mostly dependent on the visual pigment (UVS or VS) and little on the ocular media. We hypothesize that the precise spectral tuning of the ocular media is mostly relevant for detecting weak UV signals, e.g. in dim hollow-nests of passerines and parrots. The correlation between eye size and UV transparency of the ocular media suggests little or no lens pigmentation. Therefore, only small birds gain the full advantage from shifting pigment sensitivity from VS to UVS. On the other hand, some birds with VS pigments have unexpectedly low UV transmission of the ocular media, probably because of UV blocking lens pigmentation.

Hydrophilic porous poly(sulfone) membranes modified by UV-initiated polymerization for vanadium flow battery application

Hydrophilic porous poly (sulfone) (PSF) membranes were prepared and first employed in vanadium flow battery (VFB) operation. In this study, sodium p-styrene sulfonate (NaSS) was grafted on PSF phase inversion membranes by UV-initiated vinyl monomer polymerization. The grafting degree (GD) of PSF membranes was adjusted via controlling the wavelength of ultraviolet light, the concentration of photo-initiator and the irradiation time. The effect of GD on the membranes' hydrophilicity as well as their performance in VFB was studied in detail. It was proved that under the given condition, longer UV-irradiation time could induce membranes with higher GD, which led to more hydrophilic membranes. Under VFB operating condition, the membranes exhibited lower area resistance and higher ions permeability. As a result, the VFBs fabricated with the membranes showed relatively high voltage efficiency and low columbic efficiency. The membranes with controlled performance in VFB can be realized via adjusting their hydrophilicity.

Photocatalytic digestion of total phosphorus utilising nanotitanium dioxide photocatalyst

Thermal-assisted ultraviolet (UV) and H2O2-assisted UV photocatalytic oxidation methods utilizing nano-TiO2 photocatalyst are presented for the digestion of total phosphorus (TP) in water. The photocatalytic experiments for TP digestion were conducted using a 365 nm wavelength UV light, and TiO2 nanoparticles immobilized on a silicon wafer as the photocatalyst. The effects of H2O2 and temperature on the UV photocatalytic oxidation process are explained. The pseudo-first-order rate constants k of two phosphorus compounds for the UV digestion processes were obtained according to the pseudo-first-order equation. Both H2O2 and heating could improve the efficiency of the UV photocatalytic oxidation method. But by comparison, the enhancement of heating on the UV photocatalysis process is more distinctly than H2O2. In addition, the thermal-assisted UV digestion process will not lead to secondary pollution since no oxidant is needed in this digestion process, which makes it more compatible with electrochemical detection of TP. The thermal-assisted UV digestion method was employed for the digestion of real water samples. Compared with the conventional thermal digestion method for TP detection, this thermal-assisted UV digestion process decreased the digestion temperature from 120°C to 60°C within the same time, which enable the digestion process work at normal pressure.

Characterisation of the p53-Mediated Cellular Responses Evoked in Primary Mouse Cells Following Exposure to Ultraviolet Radiation

Exposure to ultraviolet (UV) light can cause significant damage to mammalian cells and, although the spectrum of damage produced varies with the wavelength of UV, all parts of the UV spectrum are recognised as being detrimental to human health. Characterising the cellular response to different wavelengths of UV therefore remains an important aim so that risks and their moderation can be evaluated, in particular in relation to the initiation of skin cancer. The p53 tumour suppressor protein is central to the cellular response that protects the genome from damage by external agents such as UV, thus reducing the risk of tumorigenesis. In response to a variety of DNA damaging agents including UV light, wild-type p53 plays a role in mediating cell-cycle arrest, facilitating apoptosis and stimulating repair processes, all of which prevent the propagation of potentially mutagenic defects. In this study we examined the induction of p53 protein and its influence on the survival of primary mouse fibroblasts exposed to different wavelengths of UV light. UVC was found to elevate p53 protein and its sequence specific DNA binding capacity. Unexpectedly, UVA treatment failed to induce p53 protein accumulation or sequence specific DNA binding. Despite this, UVA exposure of wild-type cells induced a p53 dependent G1 cell cycle arrest followed by a wave of p53 dependent apoptosis, peaking 12 hours post-insult. Thus, it is demonstrated that the elements of the p53 cellular response evoked by exposure to UV radiation are wavelength dependent. Furthermore, the interrelationship between various endpoints is complex and not easily predictable. This has important implications not only for understanding the mode of action of p53 but also for the use of molecular endpoints in quantifying exposure to different wavelengths of UV in the context of human health protection.

The Effects of Different Wavelength UV Photofunctionalization on Micro-Arc Oxidized Titanium

Many challenges exist in improving early osseointegration, one of the most critical factors in the long-term clinical success of dental implants. Recently, ultraviolet (UV) light-mediated photofunctionalization of titanium as a new potential surface treatment has aroused great interest. This study examines the bioactivity of titanium surfaces treated with UV light of different wavelengths and the underlying associated mechanism. Micro-arc oxidation (MAO) titanium samples were pretreated with UVA light (peak wavelength of 360 nm) or UVC light (peak wavelength of 250 nm) for up to 24 h. UVC treatment promoted the attachment, spread, proliferation and differentiation of MG-63 osteoblast-like cells on the titanium surface, as well as the capacity for apatite formation in simulated body fluid (SBF). These biological influences were not observed after UVA treatment, apart from a weaker effect on apatite formation. The enhanced bioactivity was substantially correlated with the amount of Ti-OH groups, which play an important role in improving the hydrophilicity, along with the removal of hydrocarbons on the titanium surface. Our results showed that both UVA and UVC irradiation altered the chemical properties of the titanium surface without sacrificing its excellent physical characteristics, suggesting that this technology has extensive potential applications and merits further investigation.

Thermal Assisted UV Digestion Utilizing Nano-TiO<sub>2</sub> Photocatalyst for the Detection of Total Phosphorous

This work presents a novel thermal assisted ultra-violet (UV) photocatalysis oxidation method for total phosphorus (TP) detection. A 365nm wavelength UV light was used as the UV light source, and the TiO2 particles, immobilized on silicon wafer, were used as the catalyst. The sodium glycerophosphate was digested as the typical compound of TP. The digested samples were determined by spectrophotometry after the phosphomolybdenum blue reaction. The catalyst can be used repetitively with long-term stability in this work. For the photocatalysis digestion process under room-temperature, when the reaction time reached 120min, the conversion rates were 92.31% and 93.66% for 1mg/L and 4mg/L of C3H7Na2O6P solutions, respectively. And conversion rates were 95.48% and 99.37% respectively for thermal assisted ultra-violet (UV) photocatalysis digestion process at the condition of 30min and 60°C. Compared with the conventional thermal digestion method and photocatalysis digestion method for TP detection, this thermal assisted UV digestion method can greatly decrease the digestion time and enhance the efficiency.

PARADOX OF UV VISION IN RAPTORS RESOLVED

Unlike humans, most birds have photoreceptor pigments that are sensitive to ultraviolet (UV) light, which has short wavelengths of 300–400 nm. However, for raptors such as kestrels, the purpose of this UV vision has remained elusive and puzzling. Over 15 years ago, when scientists found that the urine from Finnish voles reflected UV light, it seemed the mystery had been solved – UV vision was useful for scouting out good hunting grounds based on the abundance of UV-reflecting pee. However, 10 years later, studies suggest that the raptors' UV pigments are almost insensitive to UV and at best only detect UV light with longer wavelengths nearer 400 nm. Instead of benefiting raptor predators, UV light might be of more use to another type of prey, songbirds. These small birds have UV pigments sensitive to short wavelengths as well as UV-reflecting plumage. If raptors are truly insensitive to UV, then songbirds can use their feathers to secretly communicate with other songbirds. But are the raptors completely unaware of these UV signals or can they still use UV for hunting? With this controversy unsolved, Olle Lind, a post-doc in Almut Kelber's lab at Lund University, Sweden, decided to investigate with the help of two PhD students, Mindaugas Mitkus and Peter Olsson (p. 1819).Lind realised that a missing key in this puzzle was that no one knew what wavelengths of light make it to the raptors' retinas: ‘Even before the light hits the retina, it's filtered through the cornea, the lens and the fluids within the eye. The whole ocular media acts as a cut-off filter and sets UV sensitivity automatically – if you can't get it [UV] to the retina, you won't be able to detect it!’ says Lind. Using eyes from euthanised raptors, the team measured how much UV was getting through the ocular media: ‘we excised the eye and then took away a piece from the back of the eye. We were then able to shine light through the eye, which wasn't stopped by the retina and at the back of the eye we had a probe instead’, explains Lind. They found that raptor eyes cut out a lot of UV light, with only UV light of higher wavelengths making it through to the retina. In one raptor, the red kite, most of the UV reaching the retina had a wavelength higher than 394 nm.So, perhaps vole urine reflects UV light with higher wavelengths? To test this, the team collected urine from voles they had trapped in the surrounding countryside, and measured how much UV light the urine reflected – but it didn't. Lind admits that he was not entirely surprised – many other studies have characterised mammalian urine and found that it does not reflect UV. However, knowing the sensitivity of the raptor's pigments and using his newly collected measurements – UV transmittance to the retina and UV reflectance from vole urine – Lind was able to model whether vole urine can be informative in some way to raptors. He concludes: ‘there is definitely no information in the UV, they can't use UV to find vole urine – at least not with Swedish voles!’So what about songbirds? Is enough UV light getting to the retina for the raptors to eavesdrop on communicating songbirds? Using previously collected data characterising UV reflectance of songbirds' plumage and their raptor-eye model, Lind says, ‘UV markings are not invisible to raptors; they can see them, but they might not be as conspicuous to them as they are to songbirds.’ So it would seem that raptors are neither blind nor highly sensitive to UV, and the question still remains – what are these UV-sensitive pigments doing in raptors?

Application of Long Wavelength Ultraviolet Radiation for Modification and Patterning of Protein-Repelling Monolayers

The applicability of long wavelength (390 nm) ultraviolet (UV) light for controlled modification of protein-repelling oligo(ethylene glycol) terminated alkanethiolate (OEG-AT) monolayers on gold was studied. It was found that these films can be modified in a controlled way even at such a long wavelength, which offers versatile strategies for the design of mixed monomolecular films and chemical lithography. Using the UV treatment, protein affinity of the OEG-AT film could be either directly adjusted for nonspecific adsorption or, in combination with subsequent exchange reactions for molecules bearing a specific receptor, precisely tuned for specific adsorption. The parameters of both procedures were determined, and the results were compared with analogous data for UV light with shorter wavelengths. It occurred that 390 nm UV light is especially well suited for the fabrication of specific protein patterns. In addition, because of the long wavelength, well-developed standard optics and commercial patterning ...

NF-κB-Dependent Role for Cold-Inducible RNA Binding Protein in Regulating Interleukin 1β

The cold inducible RNA binding protein (CIRBP) responds to a wide array of cellular stresses, including short wavelength ultraviolet light (UVC), at the transcriptional and post-translational level. CIRBP can bind the 3'untranslated region of specific transcripts to stabilize them and facilitate their transport to ribosomes for translation. Here we used RNA interference and oligonucleotide microarrays to identify potential downstream targets of CIRBP induced in response to UVC. Twenty eight transcripts were statistically increased in response to UVC and these exhibited a typical UVC response. Only 5 of the 28 UVC-induced transcripts exhibited a CIRBP-dependent pattern of expression. Surprisingly, 3 of the 5 transcripts (IL1B, IL8 and TNFAIP6) encoded proteins important in inflammation with IL-1β apparently contributing to IL8 and TNFAIP6 expression in an autocrine fashion. UVC-induced IL1B expression could be inhibited by pharmacological inhibition of NFκB suggesting that CIRBP was affecting NF-κB signaling as opposed to IL1B mRNA stability directly. Bacterial lipopolysaccharide (LPS) was used as an activator of NF-κB to further study the potential link between CIRBP and NFκB. Transfection of siRNAs against CIRBP reduced the extent of the LPS-induced phosphorylation of IκBα, NF-κB DNA binding activity and IL-1β expression. The present work firmly establishes a novel link between CIRBP and NF-κB signaling in response to agents with diverse modes of action. These results have potential implications for disease states associated with inflammation.

Fibrinogen, Riboflavin, and UVA to Immobilize a Corneal Flap – Molecular Mechanisms

Tissue glue containing fibrinogen (FIB) and riboflavin (RF), upon exposure to long wavelength ultraviolet light (UVA, 365 nM) has been proposed potentially to solve long-standing problems presented by corneal wound and epithelial ingrowth side-effects from laser-assisted in situ keratomileuis (LASIK). Data presented in a previous study demonstrated an ability of FIB + RF + UVA to adhere two stromal surfaces; however, to our knowledge no molecular mechanisms have been proposed to account for interactions occurring between corneal extracellular matrix (ECM) and tissue glue molecules. Here, we document several covalent and noncovalent interactions between these classes of macromolecules. SDS-PAGE and Western blot techniques were used to identify covalent interactions between tissue glue molecules and corneal ECM molecules in either the presence or absence of RF and UVA, in vitro and ex vivo. Surface plasmon resonance (SPR) was used to characterize noncovalent interactions, and obtain k(a), k(d), and K(D) binding affinity values. SDS-PAGE and Western blot analyses indicated that covalent interactions occurred between neighboring FIB molecules, as well as between FIB and collagen type I (Coll-I) proteins (in vitro and ex vivo). These interactions occurred only in the presence of RF and UVA. SPR data demonstrated the ability of FIB to bind noncovalently to corneal stroma molecules, Coll-I, decorin, dermatan sulfate, and corneal basement membrane molecules, laminin and heparan sulfate--only in the presence of Zn(2+). Covalent and (zinc-mediated) noncovalent mechanisms involving FIB and stromal ECM molecules contribute to the adhesion created by FIB + RF + UVA.

Synthesis and Thermal Transport Studies of Nanofluids Based on Metal Decorated Photochemically Oxidized Multiwalled Carbon Nanotubes

Nanoparticle fluid suspensions were prepared using photochemically functionalized multiwalled carbon nanotubes in polar base fluids. Multiwalled carbon nanotubes prepared by catalytic chemical vapour deposition technique have been functionalized by irradiating with ultraviolet light of wavelength 254 nm. The photochemical oxidation of multiwalled carbon nanotubes under UV irradiation introduces oxygen containing functional groups onto the surface of the nanotubes, generating new defects on their structure. Silver nanoparticles have been deposited over multiwalled carbon nanotubes by chemical method. The enhancement in thermal conductivity of the prepared nanofluids using functionalized multiwalled carbon nanotubes and Ag nanoparticles deposited functionalized multiwalled carbon nanotubes with volume fraction, temperature and aspect ratio has been demonstrated. Silver deposited functionalized multiwalled carbon nanotubes based nanofluids in DI water with 0.02% volume fraction exhibit a thermal conductivity enhancement of 9.9% and 47% at room temperature and at 50 degrees C respectively.

Controlled Modification of Protein-Repelling Self-Assembled Monolayers by Ultraviolet Light: The Effect of the Wavelength

Exposure of protein-repelling oligo(ethylene glycol) (OEG) terminated alkanethiolate (AT) monolayers to ultraviolet (UV) light results in the damage of the OEG chains and photooxidation of the thiolate headgroups, which can be used for controlled tuning of protein-repelling properties within the so-called UV direct writing (UVDW) approach or for the preparation of mixed OEG-AT/specific-receptor films by so-called UV-promoted exchange reaction (UVPER). Using several model systems, we studied the effect of the wavelength (254–365 nm) on the course and efficiency of UVDW and UVPER applied to different OEG-AT matrices. The cross sections of the UV-induced damage were found to decrease significantly with increasing wavelength of UV light. In accordance with this behavior, the efficiencies of both UVDW and UVPER were maximal at a wavelength of 254 nm, somewhat lower at 313 nm, and lowest at 365 nm. Both UVDW and UVPER allowed a fine-tuning of protein affinity for nonspecific and specific adsorption, respectively, but UVDW did not occur below a certain, wavelength-dependent threshold dose. Performing UVPER below this dose enables us to suppress possible nonspecific adsorption of proteins even in the case of noncomplete exchange of the UV-damaged molecules of the primary OEG-AT matrix by receptor-bearing moieties. The obtained results are of direct relevance for the preparation of high-quality mixed OEG-AT/specific-receptor films and the fabrication of complex protein patterns by UVDW and UVPER lithography.

Organic photodetectors based on transparent electrodes for application in ultraviolet light detection

A high performance heterojunction organic ultraviolet photodetector based on NPB and Bphen has been fabricated. A transparent conducting polymer PEDOT:PSS coated quartz substrate instead of ITO coated glass substrate as anode is propitious to detect shorter wavelength ultraviolet light. As a result, the device shows a low dark current density, a high responsivity of 502 mA/W and a detectivity of 2.67×1012 cm Hz1/2/W which is illuminated by a 220 nm ultraviolet light with an intensity of 1.6 mW/cm2. Moreover, the performance of the PEDOT:PSS transparent electrode device is better than the semi-transparent Al electrode device electrode because of the higher transmittance and electrode properties.

Brush-Shaped ZnO Heteronanorods Synthesized Using Thermal-Assisted Pulsed Laser Deposition

Brush-shaped ZnO heteronanostructures were synthesized using a newly designed thermal-assisted pulsed laser deposition (T-PLD) system that combines the advantages of pulsed laser deposition (PLD) and a hot furnace system. Branched ZnO nanostructures were successfully grown onto CVD-grown backbone nanowires by T-PLD. Although ZnO growth at 300 °C resulted in core-shell structures, brush-shaped hierarchical nanostructures were formed at 500-600 °C. Materials properties were studied via photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations. The enhanced photocurrent of a SnO(2)-ZnO heterostructures device by irradiation with 365 nm wavelength ultraviolet (UV) light was also investigated by the current-voltage characteristics.

A mechanism of solar cell degradation in high intensity, high temperature space missions

ABSTRACTThe behavior of standard space photovoltaic assemblies in a high intensity, high temperature environment (HIHT) is addressed. Experimentally, an HIHT environment, typical for missions to the inner planets of the solar system such as Mercury, characterized by temperatures of 500K and 11 solar constant irradiance in the ultraviolet region below 400 nm, was simulated in a vacuum. Independently of the triple junction cell technology used, module degradation up to 20% in power was observed during several hundred hours of test. Electroluminescence analysis identified discrete top cell shunts close to the cell edge, in particular around the frontside contact pads. Cross‐sectional transmission electron microscopy performed on several degraded cells revealed an etched contact pad metallization/cap layer interface and more importantly, several 100‐nm large, oriented Cu3P inclusions at the shunted locations. A chemical degradation mechanism is proposed. Short wavelength ultraviolet light interacting with polysiloxanes used as module encapsulant produces hydrogen and methyl radicals. With these building blocks, an organic acid can be formed on external reaction surfaces such as the Ag busbars that simultaneously serve as a source of oxygen. Cu traces present in the Ag segregate to the surface and are transported by this acid to the contact pad of the cell in the liquid phase. An adapted cell design was developed to prevent this degradation mechanism believed to be of relevance for all HIHT space environments. A several hundred micrometer‐wide rim composed of the outermost cell area is electrically separated from the inner cell area and provides a barrier against environmental attack. None of the photovoltaic assemblies featuring this mesa cell design showed any fill factor‐induced power degradation any more. Copyright © 2011 John Wiley & Sons, Ltd.

Experimental study on ozone photolytic and photocatalytic degradation of H 2S using continuous flow mode

A foam nickel support was coated with TiO 2 sols containing anatase particles. The malodorous compound, hydrogen sulfide (H 2S), was removed via photolytic and photocatalytic oxidation processes under ambient conditions using a self-made photoreactor with 185-nm ozone (O 3) lamp illumination. The reactor degraded H 2S with high removal efficiency. The effects of several factors, such as initial H 2S concentration, ultraviolet light wavelength, relative humidity (RH), oxygen content, and catalyst deactivation and regeneration, on H 2S degradation were investigated. The highest activity for H 2S destruction was achieved with 80% RH, 21% oxygen content, approximately 200 mg/m 3 initial concentration, and 185-nm O 3 lamp illumination, resulting in higher conversion. Sulfur (S 0) and sulfate ion (SO 4 2−) were detected as byproducts via the XPS technique. The catalytic activity was improved by SO 4 2− promotion, but reduced by S 0 accumulation on the photocatalyst surface. In addition, by increasing the amount of SO 4 2− generated, the yield of S 0 and catalyst poisoning could be controlled in the reaction.

New Ultraviolet Photodetector Based on Individual Nb2O5 Nanobelts

AbstractAlthough human eyes are quite insensitive to ultraviolet (UV) light, most of the longer wavelength UV light (the UV‐A band between 320 and 400 nm) does reach the earth surface and after prolonged exposure, the radiation can cause health concerns especially skin cancer. Therefore, it is extremely important to explore ways to effectively monitor the radiation. Herein we report for the first time a new high‐performance UV photodetector made of an individual Nb2O5 nanobelt. Quasi‐aligned Nb2O5 nanobelts 100–500 nm wide and 2–10 μm long were synthesized using a hydrothermal treatment of a niobium foil in a KOH solution followed by proton exchange and calcination treatment. A nanostructured photodetector was constructed from an individual Nb2O5 nanobelt and its optoelectronic properties were evaluated. The detector exhibited linear photocurrent characteristics, excellent light selectivity, and high external quantum‐efficiency (EQE) of 6070%. Long‐term stability of the photocurrent over a period of 2500 s at an applied voltage of 1.0 V was achieved. The photodetector performance was further enhanced by improving the crystallinity and eliminating the defects in the Nb2O5 nanobelt crystals. These excellent optoelectronic properties demonstrate that Nb2O5 nanobelts are suitable for visible‐blind UV‐light sensors and optoelectronic circuits, especially those operating in the UV‐A range.