Clay minerals protect bacteriophage PBS1 ofBacillussubtilisagainst inactivation and loss of transducing ability by UV radiation

2000 ◽  
Vol 46 (8) ◽  
pp. 770-773 ◽  
Author(s):  
C Vettori ◽  
E Gallori ◽  
G Stotzky
Keyword(s):  
Bacillus Subtilis ◽  
Clay Minerals ◽  
Uv Radiation ◽  
Uv Light ◽  
Selective Media ◽  
Order Of Magnitude ◽  
Transduction Frequency ◽  
Free Phage

The effect of UV radiation on the survival of and transduction by phage PBS1 of Bacillus subtilis, free or adsorbed on the clay minerals montmorillonite (M) and kaolinite (K), was studied. After free or clay-associated phage (~107PFU·mL-1) was irradiated with UV light (254 nm) for 0, 1, 2, 5, 10, and 30 min and then allowed to infect B. subtilis FB300 (thiB4 metA29 argF4 Rfmr), the phage was titered, and Met+transductants were enumerated on selective media. After 1 min of irradiation, the titer of free and clay-associated phage decreased significantly (~1.6 times for free phage, and ~ 4.9 and 6.8 times for M and K, respectively), whereas the transduction frequency increased significantly (~3 times for free phage and ~ 1.4 and 2.2 times for M and K, respectively). The titer and transduction frequency of clay-associated phage remain essentially constant between 1 and 10 min of irradiation, whereas the titer of free phage decreased by ~1 order of magnitude after 5 min of irradiation. When free phage was irradiated for 10 min, the titer and transduction frequency decreased by ~ 2 and 0.5 orders of magnitude, respectively, whereas 30 min of irradiation was necessary to obtain comparable decreases with clay-associated phage. These results indicated that phages are protected to some extent from UV radiation when adsorbed on clay minerals.Key words: UV, transduction, phage PBS1 of B. subtilis, clay.

UV Irradiation of Shell Eggs: Effect on Populations of Aerobes, Molds, and Inoculated Salmonella typhimurium

1997 ◽  
Vol 60 (6) ◽  
pp. 639-643 ◽  
Author(s):  
FUENG-LIN KUO ◽  
JOHN B. CAREY ◽  
STEVEN C. RICKE
Keyword(s):  
Salmonella Typhimurium ◽  
Uv Radiation ◽  
Uv Light ◽  
The Other ◽  
Uv Exposure ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Fluorescent Light ◽  
Uv Treatment ◽  
Shell Eggs

The effects were investigated of 254-nm UV radiation on populations of Salmonella typhimurium, aerobes, and molds on the shells of eggs. In the first experiment, the CFU of attached S. typhimurium cells on unwashed clean shell eggs were determined after 0, 1, 3, 5, and 7 min of UV treatment (620 μW/cm2) on both ends of the egg. All UV treatments significantly reduced S. typhimurium CFU (P < .01). UVtreatment (620 μW/cm2) in 1-min alternating light and dark cycles for 5 min (three light and two dark) was compared to 0, 3, and 5 min of UV treatment. No significant differences in microbial populations were observed among light and dark cycles and the other UV treatments. In a subsequent experiment, the same UV treatments were utilized to evaluate photoreactivation. After UV exposure, eggs were exposed to 1 h of fluorescent light or I h of darkness or cultured immediately. S. typhimurium CFU were significantly (P < .01) reduced by the UV treatments. However, no significant differences between microbial populations exposed to UV treatment and UV radiation plus photoreactivation were detected. For studies of aerobic bacteria and molds, different UV treatment times (0, 15, and 30 min) at the intensity of 620 μW/cm2 and different intensities (620, 1350, and 1720 μW/cm2) for 15 min were evaluated. Mold CFU per egg were either 0 or 1 for all UV treatments and a 99% reduction of CFU of aerobic bacteria per egg were observed for all UV treatments. It appears from these studies that UV light can significantly reduce populations of S. typhimurium, aerobes, and molds on shell eggs.

MICROSTRUCTURE ANALYSIS OF MOSO BAMBOO (Phyllostachys pubescens MAZEL) SURFACE AFTER UV RADIATION

2019 ◽  
Vol 27 (01) ◽  
pp. 1950090
Author(s):  
HAIXIA YU ◽  
XIN PAN ◽  
WEIMING YANG ◽  
WENFU ZHANG ◽  
XIAOWEI ZHUANG
Keyword(s):  
Uv Radiation ◽  
Cell Walls ◽  
Uv Light ◽  
Parenchyma Cell ◽  
Moso Bamboo ◽  
Thick Wall ◽  
Phyllostachys Pubescens ◽  
Thin Wall ◽  
Intercellular Spaces ◽  
Parenchyma Cell Walls

Bamboo material is widely used in outdoor applications. However, they are easily degraded when exposed to sunlight, their smooth surface will gradually turn to rough, and small cracks will appear and finally develop to large cracks. The paper presents a first-time investigation on the microstructure changes in the tangential section of Moso bamboo (Phyllostachys pubescens Mazel) radiated by artificial UV light. The results showed that the cracks mainly appeared at intercellular spaces of fibers where lignin content was high, the parenchyma cell walls and neighbor pits where the cell wall was very thin and more vulnerable than the other parts. In addition, the part of raised area and pit cavity tended to absorb more UV light radiation and showed more and larger cracks than the otherwhere. Cracks at the intercellular spaces of fibers were larger and bigger than those on the parenchyma cell walls. The cracks on the pits of the parenchyma cell walls normally appeared at one pit and then extended to the several surrounding pits. Bordered pits cavity showed more and larger cracks than the pits on the thin wall cells. The simple pits on the thick wall cells and the fiber cells were unaffected by UV radiation.

scholarly journals Study of the Response of a Biofilm Bacterial Community to UV Radiation

1999 ◽  
Vol 65 (5) ◽  
pp. 2025-2031 ◽  
Author(s):  
Mohamed O. Elasri ◽  
Robert V. Miller
Keyword(s):  
Uv Radiation ◽  
Protective Property ◽  
Uv Light ◽  
Planktonic Cells ◽  
Light Production ◽  
Whole Cell Biosensor ◽  
Uv C ◽  
Cell Biosensor ◽  
Biofilm Matrix ◽  
Alginate Matrix

ABSTRACT We have developed a bioluminescent whole-cell biosensor that can be incorporated into biofilm ecosystems. RM4440 is a Pseudomonas aeruginosa FRD1 derivative that carries a plasmid-basedrecA-luxCDABE fusion. We immobilized RM4440 in an alginate matrix to simulate a biofilm, and we studied its response to UV radiation damage. The biofilm showed a protective property by physical shielding against UV C, UV B, and UV A. Absorption of UV light by the alginate matrix translated into a higher survival rate than observed with planktonic cells at similar input fluences. UV A was shown to be effectively blocked by the biofilm matrix and to have no detectable effects on cells contained in the biofilm. However, in the presence of photosensitizers (i.e., psoralen), UV A was effective in inducing light production and cell death. RM4440 has proved to be a useful tool to study microbial communities in a noninvasive manner.

scholarly journals Effects of Ultraviolet Radiation on Recycled and Virgin HDPE Corrugated Pipes Used in Road Drainage Systems

2021 ◽  
Author(s):  
Khanh Q. Nguyen ◽  
Patrice Cousin ◽  
Khaled Mohamed ◽  
Mathieu Robert ◽  
Adel El-Safty ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Uv Light ◽  
Morphological Structure ◽  
Tensile Tests ◽  
Repair Process ◽  
Thermomechanical Properties ◽  
Uv Exposure ◽  
Scanning Calorimetry ◽  
Drainage Systems ◽  
Significant Difference

Abstract High-density polyethylene (HDPE) pipe is one of the materials of interest for use in road drainage systems. The combination of ultraviolet (UV) light, temperature, and moisture can produce weak spots and lead to pipe degradation during the storage, installation, and repair process. The objective of this study was to evaluate changes in the chemical, morphological structure, and thermomechanical properties of recycled and virgin pipes under UV exposure. Laboratory accelerated aging tests were conducted by exposing pipes to UV for 3600 hours with an irradiance of 0.89 W/(m2 nm) at a wavelength of 340 nm. A cycle of 12 hours—comprised of 8 hours of UV radiation at 60°C and 4 hours of no UV radiation at 50°C corresponding to no water condensation—was performed to condition the specimens. HDPE specimens were taken out after 3600 hours and analyzed with FTIR (Fourier-transform infrared spectroscopy), SEM (scanning electron microscopy), DSC (differential scanning calorimetry), oxidative-induction time (OIT) measurements, and tensile tests. The results show that the recycled pipes maintained good properties and were not significantly affected by UV radiation, similarly to the virgin pipes. Statistical analysis using one-way analysis of variance (ANOVA) shows that there was no significant difference between tensile strength, elastic modulus, and hardness measurements before and after UV exposure. There were only a few small changes in the surface of the pipes. The addition of carbon black, antioxidants, and UV stabilizers prevented further aging of the pipes during UV exposure.

Enhancing the Strengths of Adhesion Bonds Between Composite Surface and Coating via UV Treatments

2017 ◽  
Author(s):  
R. Asmatulu ◽  
K. S. Erukala ◽  
M. M. Rahman
Keyword(s):  
Contact Angle ◽  
Uv Radiation ◽  
Uv Light ◽  
Composite Coatings ◽  
Weight Ratio ◽  
High Strength ◽  
Water Contact ◽  
Composite Surface ◽  
Adhesion Properties ◽  
Infrared Spectrometer

Field of composites is rapidly growing in many industries such as aviation, energy and automotive industries. Composites are known to have a high strength to low weight ratio. Significant improvement in the performance of coatings used in the protection of military and civil aircraft has been achieved the last thirty years. Composite coatings are exposed to many environmental conditions, which can significantly affect their properties. In this research, UV light treatment on the surface of composite was introduced to examine its effects on the adhesion properties between the coating and substrate. A cross-cut test was conducted on the composite panels to assess the adhesion of paint to the substrate after the treatments. Coating performance analyses were also carried out using a Fourier transform infrared spectrometer, water contact angle, and optical microscopic images. The first set of panels was treated with UV radiation for 0, 2, 4 and, 8 days, and the surface wettability was also assessed using the contact angle test. Two coats of paints, including a primer and top coat, were used, and the panels were exposed to UV radiation and immersed in water for 500 hrs and 1000 hrs. It was found that untreated panels showed a much higher contact angle of 106°, whereas the contact angle of panels treated with UV radiation was reduced to 47°. The cross-cut tests showed considerable flaking of the coating along the edges and squares of panels that were not treated, and very small flakes along the edges and parts of the grid square on panels that were UV treated, thus confirming the enhancement of coating adhesion between composite and coating surfaces by UV treatments.

scholarly journals The Puncture and Water Resistance of Polyurethane- Impregnated Fabrics after UV Weathering

Polymers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 15
Author(s):  
Antonella Patti ◽  
Domenico Acierno
Keyword(s):  
Experimental Data ◽  
Uv Radiation ◽  
Water Resistance ◽  
Uv Light ◽  
Crosslinking Agent ◽  
Waterborne Polyurethane ◽  
Impregnation Method ◽  
Polyurethane Dispersion ◽  
Spectroscopic Analyses ◽  
Before And After

Polyurethane is a polymer adaptable to different scientific and industrial requirements; nevertheless it is also extremely susceptible to UV radiation, which compromises the physical and mechanical functionality. In this framework, our study investigated the effect of waterborne polyurethane dispersion (WPUD) applied to a polyester (PET)-based fabric, through the impregnation method, on the puncturing and water resistance of the pristine material, before and after UV weathering. Results confirmed an increment of both features in the prepared fabrics, attributed to the PUR textile treatment; but a partially loss of the gained properties in the samples due to the UV weathering. In order to improve the efficiency of the impregnating dispersions, in protecting the durability of the treated materials, the addition of different UV light stabilizers, or/and of crosslinking agent into WPUD was also tested. From the experimental data, it can be concluded that formulations based on WPUD, containing both the crosslinker and UV organic absorber, have displayed an increment of their perforation and water resistance for the treated samples with respect to the starting textile, and contemporary have preserved the features against the UV light. Finally, microscopic and spectroscopic analyses have been performed as further characterization techniques of the samples surface.

Synthesis, Photoisomerization and Thermo-Optic Property of Azo Optically Active Polymer

2010 ◽  
Vol 663-665 ◽  
pp. 41-44
Author(s):  
Chang Hong Ge ◽  
Feng Xian Qiu ◽  
Xiao Xian Gu ◽  
Dong Ya Yang
Keyword(s):  
Uv Light ◽  
Inorganic Materials ◽  
Optical Parameters ◽  
Chiral Reagent ◽  
Vis Spectroscopy ◽  
Optic Property ◽  
Order Of Magnitude ◽  
Ft Ir ◽  
Azo Chromophore ◽  
Thermal Volume Expansion

A novel azobenzene optically polymer (P-DA) was synthesized based on the azo chromophore molecule, chiral reagent L(-)-tartaric acid, acryloyl chloride and methacrylate. The P-DA was characterized by FT-IR, UV-Vis spectroscopy, 1H NMR, DSC and TGA. The P-DA had high thermal stability up to its glass-transition temperature (Tg) of 110 oC and 5 % heat weight loss temperature of 199 oC. The UV-induced trans/cis photoisomerization and reflex-isomerization behaviors were investigated. The results indicated that the P-DA solution could undergo photochromism after irradiated by 365 nm UV light. The optical parameters: refractive index (n), the dielectric constant (ε) and thermal volume expansion coefficient (β) of P-DA were obtained. The thermo-optic coefficients are one order of magnitude larger than those of the inorganic materials, such as SiO2 (1.1×10−5 oC -1 and LiNbO3 (4×10−5 oC -1) and was larger than the organic material such as polystyrene (-1.23×10-4 oC -1) and PMMA (-1.20×10-4 oC -1). The conclusion had a little significance to develop optical communication.

scholarly journals Salate derivatives found in sunscreens block experimental autoimmune encephalomyelitis in mice

2017 ◽  
Vol 114 (32) ◽  
pp. 8528-8531 ◽  
Author(s):  
Yanping Wang ◽  
Steven J. Marling ◽  
Lori A. Plum ◽  
Hector F. DeLuca
Keyword(s):  
Animal Model ◽  
Autoimmune Disease ◽  
Experimental Autoimmune Encephalomyelitis ◽  
Uv Radiation ◽  
Uv Light ◽  
Autoimmune Encephalomyelitis ◽  
Insight Into ◽  
Experimental Autoimmune

UV light suppresses experimental autoimmune encephalomyelitis (EAE), a widely used animal model of MS, in mice and may be responsible for the decreased incidence of MS in equatorial regions. To test this concept further, we applied commercially available sunblock preparations to mice before exposing them to UV radiation. Surprisingly, some of the sunblock preparations blocked EAE without UV radiation. Furthermore, various sunblock preparations had variable ability to suppress EAE. By examining the components of the most effective agents, we identified homosalate and octisalate as the components responsible for suppressing EAE. Thus, salates may be useful in stopping the progression of MS, and may provide new insight into mechanisms of controlling autoimmune disease.

Dosimetric Assessment of Mono-Crystalline CVD Diamonds Exposed to Beta and Ultraviolet Radiation

2009 ◽  
Vol 1203 ◽  
Author(s):  
Martín Pedroza-Montero ◽  
Rodrigo Meléndrez-Amavizca ◽  
Sandra Preciado-Flores ◽  
Valery Chernov ◽  
Marcelino Barboza-Flores
Keyword(s):  
Uv Radiation ◽  
Uv Light ◽  
Dose Range ◽  
Beta Radiation ◽  
High Temperature Side ◽  
As Doping ◽  
Boron Doped ◽  
Overlapped Peaks ◽  
Silicon Doped ◽  
Dosimetric Assessment

AbstractPolycrystalline and mono-crystalline CVD diamonds have been investigated in relation to radiation dosimetry applications. In this work we report results on the thermoluminescence (TL), afterglow (AG) and dosimetric performance on two mono-crystalline CVD diamonds containing boron and silicon as doping materials. The samples were exposed to beta (Sr90/Y90) in the dose range of 0.07-8.26 Gy and UV light in the range of 200-400 nm, followed in both cases, by TL and AG read-outs. The boron doped sample exhibited one main TL peak at 130 °C and some overlapped peaks around 250 °C and the silicon doped samples exhibited two TL peaks around 148 and 286 °C after the crystals were subjected to beta radiation. UV radiation exposed samples showed two main TL peaks around 139 oC for boron doped, with overlapped components in the high temperature side, and at 220 and 355 oC for silicon doped samples. The integrated TL and AG intensities reached saturation around to 3.0 and 1.0 Gy in boron and silicon doped samples, respectively. The AG signal from boron doped samples reached saturation for around 60 s of 230 nm UV light irradiation and the silicon doped sample showed a linear response up to 10 minutes of 300 nm UV exposure with no apparent saturation for higher irradiation times. The TL/AG behavior of the present CVD diamond indicates the promising applications of these materials as TL/AG dosimeter for ionizing and UV radiation.

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