Ultravoilet Research Articles

Refractive Index-Adaptive Nanoporous Chiral Photonic Crystal Film for Chemical Detection Visualized via Selective Reflection.

Photonic crystals (PC) are of great importance in technology, especially in optics and photonics. In general, the structural color of PCs responds to external stimuli primarily by changing their periodicity. Herein, the authors report on refractive index (RI) adaptive PCs. Cross-linked cholesteric films with interconnected nanopores exhibit a very low RI without light scattering. Transparent PC films with maximum reflectance in the ultravoilet(UV)region respond to various chemicals by changing the reflective color of the PC. The authors demonstrate its unique colorimetric chemical detections of hazardous organic liquids. Loading various chemicals into nanopores significantly shifts the structural color into the visible range depending on the chemical's RI. These results are unique in that the structural color of photonic films is mediated by RI changes rather than periodicity changes. In principle, nanoporous photonic crystal films can detect the RI of a chemical substance by its unique color. In contrast to volumetric changes, this sensing mechanism offers several advantages, including durability, excellent sensitivity, fast response time, and wide detection range. These results provide useful insight into stimulus-responsive PCs. The structural color of PC films can be effectively tuned by adjusting average RIs instead of changing periodicity.

Synthesis of mycogenic silver nanoparticles by Fusarium pallidoroseum and evaluation of its larvicidal effect against white grubs (Holotrichia sp.)

In the present study, mycogenic silver nanoparticles (AgNPs) were synthesized by using Fusarium pallidoroseum biomass and its efficacy was tested against third instar white grubs (Holotrichia sp), a potent pest of sugarcane in western Uttar Pradesh (India). The AgNPs were characterized by UV (ultra voilet) – Visible Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray (EDX), Dynamic Light Scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Inductively coupled plasma mass spectroscopy (ICPMS). The UV-Vis spectroscopy showed peak at 430 nm, corresponding to AgNPs. The FESEM results also confirmed the synthesis of nano sized particles. EDX analysis result showed the optical absorption peak at 3 keV which is specific to AgNPs. The DLS result confirmed the synthesis of AgNPs with average size of 93.48 nm. FTIR analysis depicted information about all the chemical interactions of AgNPs. AFM image depicted the three dimensional conformations of AgNPs. The AgNPs were applied against third instar white grub larvae in vitro and lethal dosage (LD50) was formulated by Probit analysis, which was further validated and found to be significant at 0.05 levels by chi-square test.

The Effects of Plant Density on the Productivity of Tomato Hybrids in a Newly Developed Low Cost Naturally Ventilated Greenhouse

Looking into the variations in the design of greenhouses and cost factor, a two-span saw tooth type low cost naturally ventilated greenhouse (NVG) of 250 m2 area was designed and developed. The galvanized iron (GI) framed NVG covered with 200µ ultra-voilet (UV) stabilized plastics sheet, consisted of cross and ridge ventilation, shade net, fogging and drip irrigation systems. Effect of spacing and tomato hybrid on yield and yield attributing traits of tomato were studied under NVG. Twenty-three days old seedlings of four tomato hybrids viz. Rupali, Pusa Hybrid-2, Naveen 2000 and Avinash-2 were transplanted at three different spacing (60 x 60 cm, 45 x 45 cm and 60 x 45 cm) inside the NVG. The results showed that increasing the spacing significantly increased the number of fruits, average fruit weight, fruit yield per plant, yield per unit area (kg/m2) and marketable fruit yield per plant. It was noted that the significantly highest fruit yield was recorded under wider spacing of 60 x 60cm over other spacings. Among the different tomato hybrids, Naveen-2000 significantly produced higher yield (12.55 kg/m2) and yield attributes over other and statistically at par with Avinash (12 kg/m2). The developed NVG was indigenous, simple to erect and performed well for tomato crop production. The efforts will enhance the application of greenhouse in arid and semi-arid regions of India.

Response surface optimization of prodigiosin production by mutagen-treated Serratia marcescens in different growth media

Background: Prodigiosin is a bioactive bacterial pigment produced by Serratia marcescens and possesses anticancer, antibiotic, antifungal, antibacterial, and immunosuppressive activities without any toxic effects on human cells. Objectives: The study was planned to optimize the effect of ultravoilet (UV) light and acridine orange (AO), as mutagens and incubation time on prodigiosin production by S. marcescens in nutrient agar broth and peptone glycerol broth. Materials and Methods: The optimization was done by constructuing a quadratic polynomial response surface model using a bifactorial central composite design. The S. marcescens starian was treated with UV light (0, 30, 60, 90, and 120 s) and various concentrations of AO (0, 50, 100, 150, and 200 μg/mL) and incubated in the selected growth media for different times (0, 15, 30, 45, and 60 h). The prodigiosin production was measured in terms of change in pH and optical density (OD) of the ethanolic extracts of culture media. Results: The prodigiosin production was found to be a significant linear and quadratic function of incubation time in both of the culture media. However, a statistically non-significant increased prodigiosin production, in terms of pH and OD of the extracts, was observed under the influence of both mutagens. The optimum values of incubation time to achieve optimal production of prodigiosin from UV light-exposed and AO-treated cultures were found to be in the range of 37–60 h, respectively. Conclusion: The pigment production was increased significantly with an increase in the incubation time. The study provides the optimum conditions for the production of prodigiosin in research and commercial field.

Microbiological characterisation and impact of suspended solids on pathogen removal from wastewaters in dairy processing factories.

In this Research Communication we investigate the microbiological profile of 12 dairy wastewater streams from three contrasting Irish dairy processing factories to determine whether faecal indicators/pathogens were present and in turn, whether disinfection may be required for potential water reuse within the factory. Subsequently, the impact of suspended solids on the inactivation efficiency of Escherichia coli via two means of ultravoilet (UV) disinfection; flow-through pulsed UV (PUV) and continuous low pressure UV (LPUV) disinfection was analysed. Faecal indicators total coliforms and E. coli were detected in 10 out of the 12 samples collected at the dairy processing factories while pathogenic bacteria Listeria monocytogenes was detected in all samples collected at 2 out of the 3 factories. Salmonella spp. was undetected in all samples. The results also indicated that organic dairy wastewater solids had an impact on the performance efficiency of the PUV system and, to a lesser extent, the LPUV system. The findings indicate that the targeting of key pathogens would be required to enable wastewater reuse (and indeed effluent discharges if regulation continues to become more stringent) and that LPUV may offer a more robust disinfection method as it appears to be less susceptible to the presence of suspended solids.

A novel ultra-thin-walled ZnO microtube cavity supporting multiple optical modes for bluish-violet photoluminescence, low-threshold ultraviolet lasing and microfluidic photodegradation

ZnO optical microcavities have shown great promise as a potential core component material/structure for ultraviolet lasers, light-emitting diodes and photonic sensors because of their outstanding optoelectronic properties. Here, we report a novel ultra-thin-walled ZnO (UTW-ZnO) microtube cavity with a wall thickness of ~750 nm, supporting multiple types of optical modes, including in-tube Fabry–Perot modes, in-wall Fabry–Perot modes and wave-guided whispering gallery modes (WG-WGMs). The free-exciton recombination rate and exciton–exciton collisions are promoted in the cavity. The intensities of near-band edge (ultravoilet (UV) light) and X-band (blue light) emission are therefore increased at least one order of magnitude in the temperature range of 0–500 °C. Meanwhile, the temperature-sensitive multicolor luminescence of the UTW-ZnO microtubes in the visible band from near-white to bluish-violet is demonstrated for the first time. Low-threshold UV lasing is also achieved in the UTW-ZnO microtube by WG-WGMs, where the excitation threshold is down to 5.50 μW. Furthermore, light harvesting in the microtube cavity is beneficial to boosting the ZnO catalytic performance for photodegradation of organic dyes. The UTW-ZnO microtube exhibits compatibility to microfluidic channels for recyclable on-chip degradation. The present work provides new opportunities to design novel tubular wide-bandgap semiconductor devices for a variety of optoelectronic applications in micro/nanophotonics.

To Study the Effect of Ultra Voilet Radiation on Diabetic Wound Healing-Comparative Study

The diabetic wounds, ulcers heal slowly and this often results in prolonged hospitalizations. Wound infections delays healing in diabetic ulcers, and thus the standard treatment includes wound dressings and use of antibiotics. However, there is increasing resistance of bacteria to antibiotics. The purpose of study was to determine the effects of ultraviolet radiation on the healing of diabetic ulcers.

INTEGRAL FIELD SPECTROSCOPY OF AGN ABSORPTION OUTFLOWS: MRK 509 AND IRAS F04250–5718

Ultravoilet (UV) absorption lines provide abundant spectroscopic information enabling the probe of the physical conditions in AGN outflows, but the outflow radii (and the energetics consequently) can only be determined indirectly. In this paper, we present the first direct test of these determinations using integral field unit (IFU) spectroscopy. We have conducted Gemini IFU mapping of the ionized gas nebulae surrounding two AGNs, whose outflow radii have been constrained by UV absorption line analyses. In Mrk 509, we find a quasi-spherical outflow with a radius of 1.2 kpc and a velocity of $\sim290$ km s$^{-1}$, while IRAS F04250$-$5718 is driving a biconical outflow extending out to 2.9 kpc, with a velocity of $\sim580$ km s$^{-1}$ and an opening angle of $\sim70^{\circ}$. The derived mass flow rate is $\sim5$ and $>1$ M$_{\odot}$ yr$^{-1}$, respectively, and the kinetic luminosity is $\gtrsim1\times10^{41}$ erg s$^{-1}$ for both. Adopting the outflow radii and geometric parameters measured from IFU, absorption line analyses would yield mass flow rates and kinetic luminosities in agreement with the above results within a factor of $\sim2$. We conclude that the spatial locations, kinematics and energetics revealed by this IFU emission-line study are consistent with pre-existing UV absorption line analyses, providing a long-awaited direct confirmation of the latter as an effective approach for characterizing outflow properties.

Evaluation of antimicrobial efficacy of garlic, tea tree oil, cetylpyridinium chloride, chlorhexidine, and ultraviolet sanitizing device in the decontamination of toothbrush.

Objective:To assess and compare the efficacy of 3% garlic extract, 0.2% tea tree oil, 0.2% chlorhexidine, 0.05% cetylpyridinium chloride, and ultravoilet (UV) toothbrush sanitizing device as toothbrush disinfectants against Streptococcus mutans.Materials and Methods:A double blind randomized controlled parallel study was done on 210 dental students. The subjects were divided into one control group using distilled water and five study groups representing 0.2% tea tree oil, 3% garlic extract, 0.2% chlorhexidine gluconate, 0.05% cetylpyridinium chloride and UV toothbrush sanitizing device. Participants were provided with new toothbrushes and toothpastes for both baseline and intervention phases. The toothbrushes were collected after two weeks for microbial analysis in both phases. The data were analysed and compared using appropriate statistical analysis.Results:On comparing pre– and post–intervention, S. mutans colony counts, a highly significant (P < 0.001) difference was observed in all the groups. Differences of 77.74 colony forming units (CFU) in tea tree oil group, 102.87 CFU in garlic group, 68.13 CFU in chlorhexidine group, 82.47 CFU in cetylpyridinium group and 42.67 CFU in UV toothbrush sanitizer group were observed. Garlic group showed the highest reduction (100%) whereas UV toothbrush sanitizer group showed the least reduction (47.4%) in S. mutans colonies.Conclusions:The antimicrobial agents used in this study effectively reduced the S. mutans counts and hence can be considered as toothbrush disinfectants to prevent dental caries. The 3% garlic was the most effective among the antimicrobial agents.

Focused ion beam induced Ga-contamination—An obstacle for UV-nanoimprint stamp repair?

Ultravoilet (UV)-nanoimprint lithography (NIL) master stamps are subject to wear due to the mechanical nature of the imprint process. To extend the useful lifespan of expensive NIL master stamps, a focused ion beam repair process is highly desirable. Due to the inevitable Ga-staining induced by the focused ion beam processing the transmissivity of repaired NIL stamps is locally degraded. In this work, the authors investigate the impact of Ga-induced transmission losses on the imprint process. Experimental results indicate that the reduced transparency mainly impacts the amplitude of bow deformations in the imprint. These deformations are strongly enhanced by Ga-staining of the master stamp. The authors present a method for quantification of such bow-deformations. The introduced bowing-factor allows to make a qualified decision on whether the occurring deformation is acceptable for the target application. The authors have achieved control over the extent of the Ga-induced bow-deformation by tuning the UV-dose applied during NIL resist exposure. The bowing-factor provides excellent guidance for adapting the required exposure-dose of the NIL resist to reduce the bow-deformation to an acceptable level. With the presented approach, the mitigation of Ga-staining induced defects in the imprint is successfully achieved.

Synthesis and enhanced swelling properties of a guar gum-based superabsorbent composite by the simultaneous introduction of styrene and attapulgite

In current study, a series of novel guar gum-graft-poly(sodium acrylate-co-styrene)/attapulgite (GG-g-P(NaA-co-St)/APT) superabsorbent nanocomposites were prepared by the simultaneous graft copolymerization of partially neutralized acrylic acid (NaA), styrene (St) and attapulgite (APT) onto natural guar gum (GG), using ammonium persulfate (APS) as the initiator and N,N'-methylene-bis-acrylamide (MBA) as the crosslinking agent. Fourier Transform Infrared (FTIR) and ultravoilet (UV) spectra confirmed that NaA and St had been grafted onto GG backbones and APT participated in the polymerization reaction. The incorporation of St and APT clearly improved the surface porous morphology of the composites as exhibited by Filed Emission Scanning Electron Microscopy (FESEM). The effect of St and APT on the swelling properties and the swelling kinetics of the developed nanocomposite was investigated. Results showed that the simultaneous incorporation of proper amount of hydrophobic co-monomer St and inorganic nano-scale APT not only obviously enhanced the swelling capacity but highly improved the swelling rate, and the nanocomposite showed better salt-resistant capability and excellent pH-stability in various pH solutions.

UV-vis absorption of the transition metal-doped SiO 2–B 2O 3–Na 2O glasses

Ultravoilet (UV)–vis absorption spectra of undoped and transition metal (TM)-doped borosilicate glasses before and after successive gamma rays irradiation are reported. Before irradiation, the undoped glass reveals UV absorption due to trace iron impurities and no visible bands whereas the TM-doped glasses show the absorption bands which are characteristic for each TM ion in the UV and visible regions. The induced absorption bands are examined and related to either intrinsic radiation-induced defects from the host base borosilicate glass or extrinsic induced defects generated from TMs. The response of the glasses to gamma irradiation is related to the creation of defect color centers, the approach of a saturation condition and/or the possible photochemical effect on TM.

Development of an actively cooled periscope head suitable for divertor observation during quasi-continuous operation of the W7-X stellarator

High power quasi-continuous operation, as foreseen, e.g. in the stellarator W7-X, makes it necessary to actively cool all in-vessel components and thus also the front end of any periscopes used to observe the plasma in the ultravoilet (UV) to infrared (IR) spectral range. In this environment, not only the shutters which are required to prevent the windows from building-up coatings with poor transmission properties during boronisation and glow discharge cleaning, but also the faceplate of the periscope and, in particular, the observation windows need to be actively cooled. An ANSYS ® study of a prototype of such a complete actively cooled periscope head, consisting of a faceplate, three windows and a rotating shutter, is being presented. Furthermore, in a follow up of a detailed theoretical investigation of the suitability of the various window materials available for the different spectral regions, using the finite element code ANSYS ®, an experimental study of the prototype design of a window which can be actively cooled by water or gas (e.g. compressed air) is being presented. For the qualification of the window design, a special high heat load vacuum chamber equipped with a Boralectric ® infrared heater was used, which allows to study its properties up to heat loads of 50 kW/m 2, using initially the window material with the worst overall design properties, namely fused silica. Our sealing design was successfully tested not only with water (over 70 heat cycles) and compressed air cooling but also with helium at a static pressure of 30 bar for central window temperatures of 400 °C.

Excitonic properties of ZnO nanocrystalline films prepared by oxidation of zinc-implanted silica

Zinc oxide nanocrystalline films with (002) preferred orientation and intense ultravoilet (UV) emission were prepared by oxidation of zinc-implanted silica at 700°C for 2 h in oxygen ambient. A TEM micrograph showed that ZnO nanocrystalline films with a thickness of about 90 nm were formed on the surface of the Zn-implanted silica substrate. The quality and excitonic properties of the ZnO nanocrystalline films were studied through absorption spectra at room temperature and photoluminescence (PL) spectra in the temperature range from 79 to 300 K. At room temperature, a strong free excitonic emission peak at 377 nm with a very weak deep-level emission can be observed. The intensity ratio of the UV near-band-edge emission to the deep-level emission can reach up to 40. The temperature-dependent PL indicated that the UV near-band-edge emission in the temperature range 79–187 K can be attributed to a free exciton (FE), a bound exciton and the one longitudinal-optical phonon replica of FE lines. The presence of a strong emission of FE lines at 79 K suggested that high-purity ZnO nanocrystalline films have been obtained.

Organosilicon deep UV positive resist consisting of poly(p-disilanylenephenylene)

A new class of positive deep ultravoilet (UV) resists consisting of poly(p-disilanylenephenylene)s was developed, in which a disilanylene unit and a phenylene unit are connected alternatively in the polymer main chain. These resists had very high etching resistance against oxygen plasma. The lithographic applications of a double-layer resist system in which the poly(p-disilanylenephenylene) film was used as the top imaging layer were examined. As a result, very high resolution and high contrast were attained. The double-layer resist technique using organosilicon deep UV positive resist appears very promising for lithographic applications.